STEP or not STEP
martin_gnu
When i begin this list in the home page i talked about DWG format.
Well in the page 34 of the STEP e-book you can see in a photo that DXF
(and therefore DWG) is a complete CAD format.
We want build an open cad format similar to DWG...
In the page 13 they tell us:
"the real importance of STEP lies in the business
drivers that are creating a new environment for manufacturing
industries in which
the opportunities offered by STEP may be realized."
STEP was born to manufacturing industries.
You take a look to the companies working in openDWG. They are all CAD/
CAM/GIS/databases companies:
http://www.opendesign.com/membership/sustain.htm
Microstation V8 works with DWG,DXF and DGN like native formats.
and export to this formats:
IGES
CGM
STEP AP203/AP240
VRLM
Parasolids
ACIS SAT
Bentley Explain STEP export like this:
"""""Application Protocols (APs) are used to exchange data. Each AP
pertains to a different application area. For example, AP227 pertains
to spatial plant technology and contains several entities pertaining
to that area, such as pipe or elbows. Also, these APs use certain
common entities known as generic resources, such as geometry and
topology, to define solid models.
AP203 applies to representations of mechanical parts and assemblies.
AP214 applies to representations of data relating to automotive
design. Present day AP203 files typically contains the boundary
representation model, assembly data, and a limited amount of other
product information. AP214 files typically contain colors, layers, and
generic resources.
The boundary representation of a model is a CAD model represented by
its boundary. For example, a surface model consists of only the
surfaces use to make the model. Solid models include geometry
information, such as surfaces, curves, and points, and topology
information, such as edges, vertices, and faces. The geometry
information provides data about the form of the model, and the
topology information provides the connectivity between these geometric
elements and the extent of the geometric elements.
STEP AP203 files are divided into different classes according to the
type of model that they represent. For example, a surface model is a
Class 2 representation, and a solid model is a Class 6."""""
Regards.
martin_gnu
Take a look to this page 83:
http://open_cad_format.googlegroups.com/web/STEPbook.pdf
Put Ford Orion in a CAD file. This is a crazy WORLDDDDDDDDDD!!!!!!!!
This kind of things are to databases like Mysql, Oracle, postgree,...
With a database server you can share this information between all
company.
Autocad and Microstation have database conections to this kind of
crazy things.
Regards.
Lars O. Grobe
> With a database server you can share this information between all
> company.
The point is that applications that share data across networks, people,
machines tend to define protocols first, formats second. That is also
why I was trying to delay a big debate on encodings - people are getting
less interested in the format, and you can change it without effort.
At the moment, people like to put shared data into database servers as
you describe it. To exchange this data, it is frequently encoded into
files, that is why people care so much about xml. It is the same with
CAD. Big installations have drawing databases, which are better called
building databases, and use regular file formats more or less for exchange.
The point is how to strucure the data. Than you can write it into a
file, archive it on tape, store it in databases.
It may appear strange to put CAD data into databases if yoy think of it
as lines. But do not forget the meaning of CAD, Computer Aided Design.
Design is not just lines. The metadata associated with these lines is
just as valuable.
CU Lars.
martin_gnu
On Oct 8, 11:07 am, "Lars O. Grobe" <gr...@gmx.net> wrote:
>
> It may appear strange to put CAD data into databases if yoy think of it
> as lines. But do not forget the meaning of CAD, Computer Aided Design.
> Design is not just lines. The metadata associated with these lines is
> just as valuable.
I didn´t know this problems. I thought in CAD only like lines, colors,
layers, and therefore for me was very easy the problem hehe.
But it´s supposed that lines, colors and layer are always the same for
all??
At least we can share that.
?it´s important share database information between all different
fields??
if it´s important this then build a CAD format for all is a very
difficult task hehe.
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
The sample put here i like a relational database with primary key in
STEP format:
ENTITY car;
make : STRING;
model : STRING;
year : INTEGER;
owner : person;
END_ENTITY;
ENTITY person;
first_name : STRING;
last_name : STRING;
END_ENTITY;
Instances of this data model that represent a 1989 Ford Orion, owned
by the
author, are encoded using the STEP file format as follows:
#1 = CAR ('Ford', 'Orion', 1989, #2);
#2 = PERSON ('Julian', 'Fowler');
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
Regards.
martin_gnu
If database in CAD files are necessary perhaps STEP XML was a good
choice:
http://xml.coverpages.org/ni2001-03-19-c.html
XML parsers are more mature to parse text i think.
Regards.
Lars O. Grobe
Hi Martin!
I would like to explain a bit of my perspective. By CAD files as a
database I mean that for me, conceptual, a CAD file contains
heterogenous information. I describe as in architecture, but it will be
similar in other fields.
I have an object. Call it entity or whatever. It often has geometric
properties (type, position, scale, rotation, ...). It often has material
properties (concrete, wood, steel, rubber, water). It has context
properties (is part of 1/5 detail drawing IV, but not visible in 1/500
scale). It has price, provider. It has an author/drawer/content creator,
drawing and review history. It may have a name, part number. It may be
just a reference to another object. It may be a text, annotation,
correction.
In many cad systems these properties have never been addressed.
Workarounds were introduced, mostly derived from paper-times. Some
people use layers to distinguish between materials, scales, or to group
objects that are supposed to appear on an output plan. Many CAD systems
than invented multiple layer systems, because projecting everything to
layers led to documents with hundred of Layers. In Vectorworks e.g.
people have one layer system to distinguish between plan-world
characteristics (e.g. is on sheet "1st floor plan") and model-world
(e.g. belongs to concrete walls). In Autocad, people frequently use a
combination of layer and color to divide their drawings. But still, just
lay two storey's plans on top of each other without making the hole
plans into groups... its a pain.
So when people say that color, layer is enough, it is often because they
are (I am too) used to workarounds. But it is a painful workaround and
makes e.g. data extraction almost impossible. That is what I mean by
metadata - it appears as line/color/layer in many drawings today because
that is what we can do with our applications.
You mentioned that while step was supported in manufacturing industries,
architectural CAD supported dwg and compatibility libraries. I think
this is the result of just the problem this group describes - no open
format. The automotive or aerospace industry e.g. have structures strong
enough to enfore open standards. So they give a standard, and the
software companies have to implement it. In e.g. building, take a small
office, five people. Be sure they already use 30% cracked software
because the licenses are far beyond their budget. If they call their
software supplier, the end up in a paid support hotline. How should they
put pressure on their CAD provider to support the standard they need?
And how should they develop this standard - ever seen a mid-scale
architectural office with an it department able to even think about such
questions? So they are told that dwg was the standard, and they are
offered to buy a solution that allows them to stay in market. Should
they say no, we want a vendor-neutral solution? So here is the visible
difference: step was designed by the costumers, implemented after the
definition of the standard. dwg was designed as the native format of one
company, and the costumers have to use it.
I think the fist time that the fine-grained structure which made dwg and
other closed formats continue to exist even though they cause all kinds
of headache and force people to stay with products even if they would
like to change has come now with the nature of open source. Here
individuals and small companies can cooperate, and this discussion here
may be an example.
Your argument for xml may be a good one as there is a number of projects
to parse and validate xml. This may leverage development. Besides that,
I do not care so much if my data is encoded in xml (files), a big
database (on whatever medium it is) or an archive of thousands of files.
xml is useful because it supports us with a big toolset to parse and
transform, things we do not have to reinvent or reimplement. I wonder if
this could e.g. solve the problem of "unordered" files as Franz showed
in his step example. Maybe a highly optimized xml transformation (that
others were kind enough to develop already) would be enough to make
something that we can use in memory out of our chaotic step file?
CU Lars.
"Martín RV (OPENGeoMap)"
>
>So when people say that color, layer is enough, it is often because they
>are (I am too) used to workarounds. But it is a painful workaround and
>makes e.g. data extraction almost impossible. That is what I mean by
>metadata - it appears as line/color/layer in many drawings today because
>that is what we can do with our applications.
>
>
would prefer other CAD format based in trees, not in layers-colors like
you say but i think it´s a difficult task to program. For example i love
ADOBE illustrator format, because it´s based in trees, not in simple
layers like Autocad.
I add a great STEP document here:
http://groups.google.com/group/open_cad_format/web/STEP_Application_Handbook.pdf
I believe that STEP is complete, but imposible to implement in CAD.
In this document there all STEP AP especification, Many companies work
only with little parts of STEP. No full implementation nowadays.
I think that we would need a surveying and architectural AP
especification...
A CAD is a crazy world hehe.
>
>Your argument for xml may be a good one as there is a number of projects
>to parse and validate xml. This may leverage development. Besides that,
>I do not care so much if my data is encoded in xml (files), a big
>database (on whatever medium it is) or an archive of thousands of files.
>xml is useful because it supports us with a big toolset to parse and
>transform, things we do not have to reinvent or reimplement. I wonder if
>this could e.g. solve the problem of "unordered" files as Franz showed
>in his step example. Maybe a highly optimized xml transformation (that
>others were kind enough to develop already) would be enough to make
>something that we can use in memory out of our chaotic step file?
>
>
>
What Franz sample do you say?
Regards.
Lars O. Grobe
> I believe that is very difficult for CAD companies build complex CADs. I
> would prefer other CAD format based in trees, not in layers-colors like
> you say but i think it´s a difficult task to program. For example i love
> ADOBE illustrator format, because it´s based in trees, not in simple
> layers like Autocad.
It is a feature I really love in formZ too. You can (sub)group layers
there, creating a hierarchical layer structure. But still it is layers,
nothing else but the digital transformation of transparent sketching
paper. I would prefer to define attributes as I need. And in the
view-setting, give selected attributes a "switches-visibility"-status
e.g. So I do not need a layer at all, if I can set "if value of
scale-attribute != 100 then visibility = FALSE;" in the view dialog,
prefereably not in a text line but a nice GUI dialog. Software can
filter by any attribute, why using layers?
> I believe that STEP is complete, but imposible to implement in CAD.
> In this document there all STEP AP especification, Many companies work
> only with little parts of STEP. No full implementation nowadays.
> I think that we would need a surveying and architectural AP
> especification...
It is enough to support only the part of step that is needed. I cannot
tell if a specific AP is needed, I did not study the existing ones
enough. But while the application would only support what it can
actually use, the format would be capable to store more. So that is what
makes it possible to use an application-independent format. Every
application has a - at least slightly - different feature set. If the
format supports a superset of the features, no information is lost. If
it supports only a subset of all the features of all applications I
start to loose.
> A CAD is a crazy world hehe.
:-)
> What Franz sample do you say?
He gave a sample showing how difficult it is too parse a step file. As
far as I understood it is possible that you read in an entity in step
that references values that are defined later in the stream. This gives
a lot of headache if you do not want to read in all the document and
"compile" it in memory than... So preprocessing this may take away
workload from the parser. But here Franz can tell us much more...
CU Lars.
martin_gnu
Hi:
On Oct 8, 2:25 pm, "Lars O. Grobe" <gr...@gmx.net> wrote:
> It is a feature I really love in formZ too. You can (sub)group layers
> there, creating a hierarchical layer structure.
Exactly the same in Adobe illustrator.
Microstation solve partially the problem in this way:
You only have layer but you can find sublayers by pattern matching
house1_window
house1_wall
house1_stairs
house2_wall
house2_window
house2_stairs
here you have 2 sublayers (house1 and house2), but no more than 1
sublayer posibility. I suppose that Bentley do this things to have
100% compatibility with DWG.
> prefereably not in a text line but a nice GUI dialog. Software can
> filter by any attribute, why using layers?
>
I think layers is a natural way to work in the world:
A base layer is a house
A room is inside a house (sublayer)
a table is inside the room (sublayer)
and so... (sublayer)
filter by any attribute is possible using trees. Illustrator let us
select by all kind of atributtes.
I believe that filter by any attribute and a layer/sublayer system is
totally compatible.
Maya, blender, k-3d and Shake work so, but they show us the layers
system like nodes widgets.
Regards.
martin_gnu
nodes widgets in maya:
http://stevenchan.us/files/tut_facingratio_surflum/17.png
Maya is the software to build all kind the 3D games and films(srek,
toy story,...) and was made in motif/openmotif.
This kind of widget i haven´t seen in GTK or Qt nowadays.
It´s more common this:
http://www.oz9aec.dk/software/gpredict/loc-tree-sign.png
This is a gtktreestore widget similar to sublayers system in
illustrator.
Franz Reiter
Ad:
> far as I understood it is possible that you read in an entity in step
> that references values that are defined later in the stream. This gives
Yes, thats correct.
You must import all at once and order it, if you want to put it into an
interpreter.
> a lot of headache if you do not want to read in all the document and
> "compile" it in memory than... So preprocessing this may take away
it took 2 months for 2 people to write the step-translator; this is not so
much.
BUT you must have native support for all types of objects you want to import
(analytical described surfaces and curves) or change it at least into a
supported type of object (eg if you cannot support a Parabola you have to
translate it into a B-Spline).
We have decided to create gCAD3D as an interpreter-system, which is completly
different from most CAD-systems.
We made the step-importer (without Express-Tool) to show that a
interpreter-system can work also with acceptable speed.
Greetings from Vienna,
(from AUSTRIA, not Germany !)
Franz
Gertwin
> I think layers is a natural way to work in the world:
> A base layer is a house
> A room is inside a house (sublayer)
> a table is inside the room (sublayer)
> and so... (sublayer)
I don't think layers are naturally, lines can only on one layer at a
time, lines on different layers can not share properties.
If the base layer is a house and the room is on a sublayer some lines
of the house has to be duplicated in the room layer.
I like to work layer independent, a line or object has a set of
properties, it is a wall or a window etc.
These properties don't include color linetype etc, it is just a name.
All these lines with there properties compiles a model, a building,
car or map.
Different people like to look at a different way to a model, you have
to define a presentation for a particular view.
A presentation consists of the properties normally found on a layer,
color, weight, style, a presentation also contains filters.
An architect, a electrician or a constructional engineer all want an
other presentation of the model.
For example the constr. eng. doesn't want to see the electric wiring
(filter), the electrician wants to see the wiring in thick lines
(presentation).
But the all want to see the holes through the construction.
If you want to achieve these things with layers many many layers has
to be used, all the different people working on the project must use
the same layers.
The more layer there are the more difficult it gets to get all lines
on the right layers, it is far more easy to bind a property to a line.
There is also a big difference between working in layers and trees.
If you want to work with trees i think this is only possible when
working with objects (root = car, branches = wheels, engine, etc.)
With trees it is more difficult/impossible to share properties between
lines, and this is important in gis, a line can not be part of a house
and also be part the grass. I don't want to use two lines to get this
done.
So is it possible to define a format suitable for all purposes?
If you look at AutoCAD it serves all but it is not very good in it (it
is good 2D production drawings).
Greetings,
Gertwin
Lars O. Grobe
> You must import all at once and order it, if you want to put it into an
> interpreter.
Do you think that using some kind of compile step would help here? I
mean a tool validating and reordering the file, so that this memory
consumer does not happen in the main app? I was wondering if the
xml-tools available would help to do so. I have to look how they solve
this problem in xml (how do they reference values in xml that are not
defined yet?).
> BUT you must have native support for all types of objects you want to import
> (analytical described surfaces and curves) or change it at least into a
> supported type of object (eg if you cannot support a Parabola you have to
> translate it into a B-Spline).
Yes, that looks like a huge task. But if one thinks not about writing
from scratch but reusing code, it gets less awful. I think that there
are already engines out there that are able to handle at least the very
most of step geometry objects (brlcad, cascade, ...). So if one binds
one of these libraries, at least the second option (converting to
something already supported) should be possible.
> We have decided to create gCAD3D as an interpreter-system, which is completly
> different from most CAD-systems.
Is this documented? I imagine something like what happens in brlcad when
using scripts to call the generator/modifier tools on the model database?
> We made the step-importer (without Express-Tool) to show that a
> interpreter-system can work also with acceptable speed.
I see.
> Greetings from Vienna,
Ah, greetings back there ;-)
CU Lars.
Lars O. Grobe
I just changed the subject line.
>> I think layers is a natural way to work in the world:
I agree if you think about "natural way to work" as sitting on a table
witch sketching paper. Which is rather productive and the reason that
using layers can work out.
>> A base layer is a house
>> A room is inside a house (sublayer)
>> a table is inside the room (sublayer)
>> and so... (sublayer)
Well, this is true in most drawings. If you enter a house you will not
perceive it as such. Layers are on top of each other, the furniture is
in the room, the room is surrounded by walls, etc. Things are not all 2d
and lying stacked as on my desktop ;-)
> So is it possible to define a format suitable for all purposes?
> If you look at AutoCAD it serves all but it is not very good in it (it
> is good 2D production drawings).
Well, the point is that if you use attributes that the user defines, it
is his decision how to use them. E.g. for a small 1:200 sketch that I
want to complete on a week-end, I may choose just to define an attribute
"layer" and use the system just as in Autocad. In a project with some
10.000s m2, that is supposed to be applied, I would like to work out a
more sophisticaded attribute system. Maybe even one allowing namespaces.
Meaning that office A can define a:materialName="wood_cherry", office b
has b:materialName"wood124" for it, occice c uses c:LAYER_MAT="Cherry"
and still one can map them and there are no conflicts between names. So
keep the user free to use attributes as layers or whatever he/she needs...
CU Lars.
Gertwin
> is his decision how to use them. E.g. for a small 1:200 sketch that I
> want to complete on a week-end, I may choose just to define an attribute
> "layer" and use the system just as in Autocad. In a project with some
> 10.000s m2, that is supposed to be applied, I would like to work out a
> more sophisticaded attribute system. Maybe even one allowing namespaces.
> Meaning that office A can define a:materialName="wood_cherry", office b
> has b:materialName"wood124" for it, occice c uses c:LAYER_MAT="Cherry"
> and still one can map them and there are no conflicts between names. So
> keep the user free to use attributes as layers or whatever he/she needs...
Yes, you are correct, if only a identifier of the layer/attribute is
stored in the element and in a separate table the attributes or layers
are maintained it is the most flexible.
Should a table in which the layers or attributes are stored be part of
our file format, has gcad3d or step such structures?
Also i want to see our file format able to store data along with the
elements, just as xdata in AutoCAD or user data in MicroStation.
I don't care if this data (also for attribute/layer) information is in
a separate file if we have some kind of "include" system that
references external files (or database links).
Greetings,
Gertwin
Lars O. Grobe
> stored in the element and in a separate table the attributes or
> layers are maintained it is the most flexible.
In xml-world, you can store more or less random text in every entity. E.g.:
<cad:geomObject>
<cad:circle center="0,0,0" radius="1"/>
<larsAnnotations:description>
This is a circle.
</larsAnnotations:description>
<larsDrawingStucture:Option visible="TRUE"/>
</cad:geomObject>
So even if the application only knows the cad:-namespace, one could have
a way to make entities from unknown namespaces visible and editable. And
one could still enable the user to define such entities as a filter
criteria e.g. to toggle visibility, line color etc. BUT I do not know
how to do this in step - I do not know about their xml encoding, would a
step/xml validate if mixed namespaces?
> Should a table in which the layers or attributes are stored be part
> of our file format, has gcad3d or step such structures?
My idea would be to use namespaces to divide ONE document. It would
allow easier handling in non-file encodings, e.g. when stored in databases.
> Also i want to see our file format able to store data along with the
> elements, just as xdata in AutoCAD or user data in MicroStation.
This generic approach would allow whatever you want.
CU Lars.
Franz Reiter
> Should a table in which the layers or attributes are stored be part of
> our file format, has gcad3d or step such structures?
ObjName(*), Linetyp/Color|Texture, Layer, Refsys, UserData(*),
Dim, Pick, Hilite, Hide, Group,
symbolic, visible, hidden.
Layer is the layerNr; 16 bit (65000 Layers max).
UserData is a pointer to a internal datafield, binary or ascii; size variable.
(*) = not yet implemented.
One elementType should be Applicationdata; eg to store csv-data; if there are
functions to correlate excel-fields with internal variables you can use
excel-sheets directly.
Not yet implemented, tested.
What do yot think about FreeCAD:
http://juergen-riegel.net/FreeCAD/Docu/index.php?title=Main_Page
(OpenCascade (Step, Iges, some Mesh-formats) + Qt + Pyton scripting;
native format is Opencascade(Ascii)+xml) ?
Franz
mar...@opengeomap.org
>
>
> What do yot think about FreeCAD:
> http://juergen-riegel.net/FreeCAD/Docu/index.php?title=Main_Page
> (OpenCascade (Step, Iges, some Mesh-formats) + Qt + Pyton scripting;
> native format is Opencascade(Ascii)+xml) ?
>
> Franz
I think that opencascade (FREECAD), BRL-CAD, Archimedes and gcad3d have a
good future.
good demos of opencascade.
http://www.opencascade.org/showroom/demos/
The problem of opencascade we have 250 Megas of source code hehe. People
need several years to study all posiblities and many people working there.
Little by little...
They are like trolltech and Qt:
A company give CAD services and offers also all source code to the community.
COMPANY services:
http://www.opencascade.com
COMMUNITY source code:
http://www.opencascade.org
Great companies like BWM and EADS use this technology.
http://www.opencascade.com/customers/
Regards.
martin_gnu
On Oct 10, 7:20 pm, Franz Reiter <franz.rei...@cadcam.co.at> wrote:
>
> Attributes (for each element) should be:
> ObjName(*), Linetyp/Color|Texture, Layer, Refsys, UserData(*),
> Dim, Pick, Hilite, Hide, Group,
> symbolic, visible, hidden.
>
> Layer is the layerNr; 16 bit (65000 Layers max).
> UserData is a pointer to a internal datafield, binary or ascii; size variable.
> (*) = not yet implemented.
>
> One elementType should be Applicationdata; eg to store csv-data; if there are
> functions to correlate excel-fields with internal variables you can use
> excel-sheets directly.
> Not yet implemented, tested.
>
Franz do you have this advices save in your documents?. I say this
because if not i save your advices for the future...
The next week we are in a magazine in spain called todolinux.
In spain people in the public administrations are forcing to give open
standards formats and the source code in all the works. In Spain if
you know we have the gvSIG software. This software is in the osgeo
cover like you can see:
http://www.gvsig.gva.es/index.php?id=gvsig&L=2
http://www.osgeo.org/
In this project there a lot of public money and they want build a free
CAD also,...
What is it happens with the standards opened up in your countries???.
In Spain we have many distributions public GNU/linux as linex,
lliurex, molinux,...
http://lliurex.net/home/ (Valencia)
http://www.linex.org/joomlaex/ (Extremadura)
http://www.guadalinex.org/ (Andalucia)
http://www.educa.madrid.org/web/madrid_linux/ (Madrid)
http://trisquel.uvigo.es/ (Vigo University)
http://pulsar.unizar.es/gluz/ (Zaragoza University)
http://www.linuxglobal.org/ (Cantabría)
http://tirwal.terueldigital.es/ (Aragon)
http://www.molinux.info/ (Castilla-La Mancha)
...
In engineering projects we have office documents and CAD documents. By
now i only see MS office (.doc,.xls,..) and DWG. I am totally sure
that from European Union they will need an open CAD format like open
office,...
Regards.
Gertwin
> because if not i save your advices for the future...
Hi Martin,
Maybe it is an idea to put the open_cad_format document chapters on
several discussion pages in this way it is more easy to discuss this
format.
I mean a page for the "introduction", for "Bases 2D-3D", for "Texts",
"Points", etc.
I think we should take this document as a start of our CAD file
format.
I think if we can provide a good/solid CAD engine library which can
and will be used by several drawing/CAD applications we have
succeeded.
It is impossible to define a standard format, it can become a sort of
standard if there is a large user base.
Greetings,
Gertwin
"Martín RV (OPENGeoMap)"
Franz do you have this advices save in your documents?. I say this because if not i save your advices for the future...Hi Martin, Maybe it is an idea to put the open_cad_format document chapters on several discussion pages in this way it is more easy to discuss this format. I mean a page for the "introduction", for "Bases 2D-3D", for "Texts", "Points", etc.
http://groups.google.com/group/open_cad_format/web/oca-page
With a google account all can edit this page using text colors, sizes,...
Regards.
Franz Reiter
ad:
> Franz do you have this advices save in your documents?. I say this
programfunctions. The programming-doc is not translated yet from german ..
i think that i can put out the next gcad-version in 2 or 3 days; this version
will have clothoids and a gis-mesh (imported from Landmark.xml).
This could be a good base for discussions around gis-format.
With the next Version i had to modify the general fileformat;
(the file is now separated by SECTION's; new is "SECTION PTAB"
and "SECTION MESH"; subModels now are in "SECTION MODEL <modelName>"
was "MODEL <modelName>" before.
Since this is the basic format i have tried to explain it in the new
http://groups.google.com/group/open_cad_format/web/oca-page
What should be improved ?
Maybe you should also provide test-examples at opengeomap or open_cad_format;
- a point file (max 50000 points)
- a corresponding file with the breaklines (dxf ?)
- the mesh for the points and breaklines (Landmark.xml ?)
- the image from googleEarth (or photo from airplane) for that area
It should be possible to depict that in the new format ..
Franz
"Martín RV (OPENGeoMap)"
this is in the programming docs and in the inlude-files for the programfunctions. The programming-doc is not translated yet from german ..
i think that i can put out the next gcad-version in 2 or 3 days; this version will have clothoids and a gis-mesh (imported from Landmark.xml). This could be a good base for discussions around gis-format.
The key is the origin of data:
From Photogrammetry.- from aerial photos. (http://www.ossim.org)
From GPS/surveying.- For terrestrial instrumentation. Many of this instruments have direct export to DXF of shapefile of ESRI(GIS).
In many cases all people uses Autocad and then sell the DXF files to a GIS company.
P20=P(-2166.3 1494.1 0)
P21=P(-1396 539.9 0)
P22=P(-39.5 1344.7 0)
P23=P(-947.7 2597.7 0)
P24=P(-1384 2206.7 0)
L20=P24 P21
L21=P21 P20
L22=P21 P22
With the next Version i had to modify the general fileformat; (the file is now separated by SECTION's; new is "SECTION PTAB" and "SECTION MESH"; subModels now are in "SECTION MODEL <modelName>" was "MODEL <modelName>" before. Since this is the basic format i have tried to explain it in the new http://groups.google.com/group/open_cad_format/web/oca-page What should be improved ?
Someone think that oca/gcad can be similar than DXF/DGW but free??. Perhaps oca/gcad wasn´t the best CAD and complete format in the world but it´s very easy to implement like openDWG and a little better than the openDWG. I would be very happy only with geometric primitives, and from this list everyone can extend the file to their necessitites. I believe that a full support of OCA is very easy like a full support to DXF.
From Autocad would be very easy build plugins to export and import this format. For me in opengeomap would be very easy build free surveying aplications using this format and after import in Autocad the files to edit and work while we don´t have a professional free CAD,...
Also it´s possible in STEP but i would need STEP examples to surveying?? We have in open_cad_format 2 STEP manuals but i can not see real STEP code, only CAD theory???.
Maybe you should also provide test-examples at opengeomap or open_cad_format; - a point file (max 50000 points)
point1 23.34 23.5 0.0 code
point2 23.34 23.5 0.0 code
point4 23.34 23.5 0.0 code
point5 23.34 23.5 0.0 code
We use points in this kind os assci files. Landxml is a new format and i haven´t used it...
- a corresponding file with the breaklines (dxf ?) - the mesh for the points and breaklines (Landmark.xml ?)
a green layer for triangles lines in a layer. 2D independent lines of autocad are triangles. In autocad we only have 1 kind of mesh based in squares not in triangles.
Breaklines in a new layer also but red. They are lines also.
The plugin uses this layer information to get the height of points or to create contour lines.
- the image from googleEarth (or photo from airplane) for that area It should be possible to depict that in the new format .. Franz
where is lars o grove, hehe. It´s important freearchitecture here. You want build architecture samples in gcad/oca or only in STEP???. In this list there are many interesting people and it´s important a real union between us. Freearchitecture people is real important for us because architect it´s an important community using a CAD.
To Franz Reiter, the last week i was talking about this list and the cad file format to Richard Stallman, do you want free your cad and that gcad was a GNU CAD??. I believe that Richard Stallman was very happy that your CAD was a GNU project. You would have an important diffusion to gcad3d. You have done a great job in this years, but i really believe that your CAD need more people. Opencascade are many people, BRL-CAD are many people, Archimedes are many people,...
Regards.
Gertwin
> >this is in the programming docs and in the inlude-files for the
> >programfunctions. The programming-doc is not translated yet from german ..
>
> German is a difficult language for us,hehe :-[
For me German is not so difficult to understand, so post this document
if you want.
> Yes in your format we can respect don´t repeat primitives like GIS.
> (nodes->arcs->faces). I believe that people uses Microstation and
> Autocad many times before work in GIS software like Arcview or Geomedia.
> People from Geomedia for example can join entitites from a DXF file. In
> your format we don´t have this problem because you can use nodes, acs
> and faces like in GIS.
I think CAD must be our primary goal.
I think GIS is shifting from files to databases, files have a limited
area, there are always problems with f.i. roads which spans over
several drawings, in databases are not limited to a paper size.
If we have a CAD module in which we can define primitives (arcs,
lines, plines etc.) and we have a separate module which exports the
oca file into a database it is a better solution than try to build a
full GIS application on top of our oca format.
If the geometry is in a Oracle, MySQL or PostGIS database the geometry
can be viewed by many GIS applications.
Also geometry can be bound to administrative records like addresses,
maintenance schemas etc.
Greetings,
Gertwin
Franz Reiter
ad
> >Maybe you should also provide test-examples at opengeomap or
> >- a corresponding file with the breaklines (dxf ?)
Breaklines: what is the source before it comes to autocad ?
> >- the mesh for the points and breaklines (Landmark.xml ?)
how do you create the mesh ?
i think AutocadCivil can export the civil-mesh as Landmark.xml;
it can be exported also as traingle/quads (dxf .).
Franz
"Martín RV (OPENGeoMap)"
On Thursday 18 October 2007 18:27, Martín RV (OPENGeoMap) wrote: adMaybe you should also provide test-examples at opengeomap orwhat kind of point files??what is used most ? can the format vary ? Please describe.
point_name x_coordinate y_coordinate z_coordinate code
All can export or import this kind of file. LandXML by now it´s not used so much...
People usually only use a software and there therefore don´t need export to landXML to exchange files.
- a corresponding file with the breaklines (dxf ?)Breaklines: what is the source before it comes to autocad ?
- the mesh for the points and breaklines (Landmark.xml ?)how do you create the mesh ? i think AutocadCivil can export the civil-mesh as Landmark.xml; it can be exported also as traingle/quads (dxf .). Franz
for example in MDT-TC-IP you have several primitives and can export all to ascci files (not landXML).
points-> format separated by tabs.
triangulation->It´s in binary format and difficult to understand. They draw lines represent this triangles in a autocad layer but they uses the binary external file...
highway axis-> represents the real way of the road using clothoids, circles and lines. Autocad don´t have clotoids and therfore they draw a clothoid by many short lines.
longitudinal profile-> ascci (point_name distance_origin height)
You get a longitudinal profile thanks to triangulation and highway axis. When you get this file you can draw in a graph inside a CAD using normal primitives. You read the profile ascci file and draw...
http://doblevia.files.wordpress.com/2007/04/perfil.png
In green you can see the terrain profile.
traverse profile-> ascci (point_name distance_origin highway_axis_distance height)
It´s the same than longitudinal profile but you get heights in perpendicular direction to the road. (-20 meters,+20 meters for examples). 0 meters is the axis of the road.
leveling highway-> similar to longitudinal profile.they are the final highway heights. The longitudinal profiles are the original terrain height before build the highway.
You define the leveling highway by parables:
y=(p1-p2)/L*(x^2/2)
where p1 is the inclination of the init line
where p2 is the inclination of the final line
L is the horizontal lenght of parable.
x is the position of a point. In the beginning is 0. At the end is L.
Usually you define the parable by Kv= (p1-p2)/L.
http://doblevia.files.wordpress.com/2007/04/perfil.png
In red you can see the real profile.
In highway axis and leveling highway you have lines right and over this lines you define the parameters os clothoids and parables.
highway section-> represents the perpendicular form of the highway with different inclination but simmetric in both sides of the way . It´s in binary format.
banking, camber-> represent the inclination in the curves to avoid cars exit the roads... It´s a value increasing when you enter in a curve and decreasing when you exit of a curve.
The final work is draw in a CAD a complete highway section every 10 meters for example. If you have 1 kilometer you have 100 draws. In MDT TC-IP you read all files to do this. The modern way is read this files from databases like mysql, postgree,... or using landxml files.
By now the only software with a full landxml support is autodesk civil. I want find this software in Emule to test but it´s difficult.
By now the great civil software was inroads (Autocad and Microstation). I think that Autodesk_civil is the future but i don´t now. Inroads work in the same way that TCP-IP.
Here you have screenshots:
http://www.orsenor.com/PROTOPO_COMPOSICION.pdf
page 7. longitudinal and leveling profiles
page 8. Complete section
page 10. highway section.
For surveying i only see like internal primitives the triangulation and points. The others are simple draws...
You always needs the points to create triangulations and you always need triangulation to do all kind of task.
Franz Reiter
> Franz Reiter escribió:
> >>>Maybe you should also provide test-examples at opengeomap or
> breaklines are lines join to triangulation points.
> >Breaklines: what is the source before it comes to autocad ?
if the surveyor wants to have some points connected with lines;
eg if there is an edge in the landscape, you want to have exactly that edge in
the mesh. Are the points marked in the points file or is there an
extra-file ?
>for example in MDT-TC-IP you have several primitives and can export all
>to ascci files (not landXML).
so the software MDT-TC-IP reads the point-files, the breaklines (source ?
format ?) and does the triangulation ?
Protopo is a ARX-program and puts the mesh directly into Autocad ?
Franz
"Martín RV (OPENGeoMap)"
clear now; are there such files in the net ?
I put a complet surveying project here:
http://groups.google.com/group/open_cad_format/web/surveying_samples.zip
We have 3 DWG files. I want to translate this 3 DWG files to oca/gcad or STEP...
We have points files (.pun)
We have triangulation files in binary(.sup)
We have .grt files. this are binary and represent the information in the profiles... In english i think this is called guitar (guitarra).
We have .eje files to the road axis using clothoids, lines and circles.
We have .lon files to the longitudinal profiles.
We have .tra files to the transverse profiles.
We have .ras files to the leveling profiles.
we have .per files to the banking, camber in a road (peralte) to the complet longitudinal profile.
We have a .scc binary file to the road section.
We have a .SEG binary file like a complete way using all before files. This .SEG is like landXML.
The transversales.dwg and longitudinal.dwg files need . SEG to draw this graphs. In the graph you can see information Below an information called guitar.
This system is used to build car roads and train ways.
breaklines are lines join to triangulation points.Breaklines: what is the source before it comes to autocad ?if the surveyor wants to have some points connected with lines; eg if there is an edge in the landscape, you want to have exactly that edge in the mesh. Are the points marked in the points file or is there an extra-file ?
for example in MDT-TC-IP you have several primitives and can export all to ascci files (not landXML).so the software MDT-TC-IP reads the point-files, the breaklines (source ? format ?) and does the triangulation ?
2- You create the breaklines layer by hand in autocad joining points by lines. You could need define an island and a contour layer.
2- You use the triangulation module. This read all points in the file and use other layers (breaklines ,island ,contour )
4- with this surface you can do all kind of task. Create contour lines, profiles, volume measurements,...
perhaps breaklines, contour and islands can be include inside the mesh. For example a line of the mesh can be normal, breakline, contour or island.
Protopo is a ARX-program and puts the mesh directly into Autocad ?
Inroads is a MDL plugin in Microstation and an ARX plugin in autocad.
Regards.