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Thanasis
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"Martín RV (OPENGeoMap)"
I have seen your cad and it seems interesting for me ;-) .
(triangulation, contour lines)
ABOUT SVG:
SVG is a standard XML and it seems interesting as format to print or for
the space paper like Autocad
Qt and GTK have good support for this format.
The format odt of OpenOffice is a ZIP file with several folders and
several XML files inside of that folders and it works faster.
ABOUT DXF:
I think that it´s very difficult open a dxf file very fast because
Autodesk build this file to avoid this kind of things... But, if all CAD
developers think like you then we should support that idea.
You can take a look to the gcad3d format. It is a pseudo-script that is
very quick and very intelligent from my point of view. It has snaps
inside the file and therefore is very precise. It´s very very easy to
program too... Software like SHAKE from apple is based in this kind of
files.
For my the most important is:
1>> It would be interesting for the new format of CAD that we can have a
library in C to be able to use freely from C++ and with bindings to
python, perl, JAVA, ruby, c#...
2>> Of course also it would be interesting to make applications with
autolisp, vba,... that they work inside Autocad, Microstation, Catia...
to import/ export this new file.
ABOUT clothoids
The curves are you talking about are called clothoids. For people like
me (www.opengeomap.org) are very interesting that kind of curves.
Microstation has clothoids like splines. We don´t have closed formulas
to that curves like you say... It´s obvious that clothoids can not be
primitives of the CAD format.
A polyline which includes circular arcs and splines i believe that is
very basic to CAD.
A question for you. dont´t you see the pythonCAD?
http://www.pythoncad.org/
Gertwin
dumped as binary strings in the dxf file so you can not use these
objects (I think the same must be true for other Autodesk products).
Did you ever thought about a (compressed) xml format?
Something like gml, the structure is based on a schema so before
reading it into a application the file can be validated, that makes it
easy to exchange files between apps.
Also in xml it is possible to bind non graphical data to elements.
I agree about the minimalistic format, you can split complex elements
as polylines (containing linear and arc segments) into basic elements,
if all the basic elements contain the same group identification a
application supporting these elements can recreate the original, if
not the application can draw the graphics without loss of visual
information.
Gertwin
martin_gnu
> Did you ever thought about a (compressed) xml format?
> Something like gml, the structure is based on a schema so before
> reading it into a application the file can be validated, that makes it
> easy to exchange files between apps.
> Also in xml it is possible to bind non graphical data to elements.
XML can be a interesting option, but someone must design the file...
All posibilities are open.
Expererience CAD developers can talk about XML, but i think that they
prefer other kind of ascci files.
take a look here:
http://groups.google.com/group/open_cad_format/web/open-cad-format
Standards Guy
As a matter of interest and possible use, check out the work on
LandXML/LandGML and CityGML.
http://www.opengeospatial.org/projects/initiatives/landgmlie
http://sourceforge.net/projects/gml2civil/
www.gmldays.com/gml2004/presentations/LandGML-DavidBurggraf.pdf
and
Finally, the Open Geospatial Consortium (OGC) has a very active 3DIM
(3D Information Modeling) Working Group. The focus of this group is
defining where and how seamless workflows can happen between/among all
the information communities that particpate in the built environment
(AEC-CAD-GIS etc).
Regards
Carl
On Sep 8, 2:19 am, martin_gnu <opengeo...@gmail.com> wrote:
> Welcome to the list Gertwin
>
> > Did you ever thought about a (compressed) xml format?
> > Something likegml, the structure is based on a schema so before
martin_gnu
> As a matter of interest and possible use, check out the work on
> LandXML/LandGML and CityGML.
>
> http://www.opengeospatial.org/projects/initiatives/landgmlie
LandXML is only use in Autodesk Civil, but autodesk use DWG... LandXML
is only a useful part to exchange data.
This format is destinate to 3D Gis. A CAD is very different. We had
WRML too.. city3D works fine with big files?¿?¿?¿?
A CAD format can be compatible to tools like blender3d, but not GIS or
surveying.
Blender3D by now only works in native file, not XML.
The most interesting XML by now for me is SVG, but we would need add
3D to the format.
but if Autodesk and Bentley use a native file to work. can we use an
XML?. I think that this big companies study the posibilities of work
in XML like native file,...
We would need see a XML CAD file working so fast than DWG in Autocad
or DGN in Microstation. Perhaps a XML CAD format was good to exchange
data but not to work inside the CAD. Autodesk design the LandXML, but
do they want design a XML CAD format?, I don´t believe, jeje
Mi opinion about the future is:
Create a simple CAD format with a free CAD software, without 3D
modeling. We have blender to 3D modeling. Autocad and Microstation
lose the time with modeling utilies. A CAD is a CAD, and a 3D model
software is a 3D model software.
Create a format to compatibility with GIS community. This
compatibility comes from a plugin to export to GML,
city3D,LandXML,...etc
Regards.
Gertwin
> Hi
>
> > As a matter of interest and possible use, check out the work on
> > LandXML/LandGML and CityGML.
>
> >http://www.opengeospatial.org/projects/initiatives/landgmlie
>
> LandXML is only use in Autodesk Civil, but autodesk use DWG... LandXML
> is only a useful part to exchange data.
>
> >www.citygml.org
>
> This format is destinate to 3D Gis. A CAD is very different. We had
> WRML too.. city3D works fine with big files?¿?¿?¿?
>
> A CAD format can be compatible to tools like blender3d, but not GIS or
> surveying.
> Blender3D by now only works in native file, not XML.
>
> The most interesting XML by now for me is SVG, but we would need add
> 3D to the format.
Maybe a subset of the "Universal 3D File Format" (http://www.ecma-
international.org/publications/standards/Ecma-363.htm) can be a
starting point for a file format, not a binary format but a text
variant of it.
>
> but if Autodesk and Bentley use a native file to work. can we use an
> XML?. I think that this big companies study the posibilities of work
> in XML like native file,...
>
> We would need see a XML CAD file working so fast than DWG in Autocad
> or DGN in Microstation. Perhaps a XML CAD format was good to exchange
> data but not to work inside the CAD. Autodesk design the LandXML, but
> do they want design a XML CAD format?, I don´t believe, jeje
MicroStation can not use a xml file format because every action in MS
is written to the design file and they need to search elements fast
(index).
Constant update of the design file has an advantage, no data is lost
in case of a run time error, the disadvantage is that a binary file
has to be used.
For AutoCAD i think xml is usable, the dwg is read into memory, all
actions are only done in memory until the dwg is saved. So for AutoCAD
only the load and save time will increase (dxf like performance). I
think AutoCAD will not make its document format open/readable, just to
keep the Open Design Alliance busy.
I think the data structures in wich the data is read are also of
interest, the performance of a application depends on it.
For large models you need to use some kind of index to query elements
in cases you can not use opengl/mesa.
It must be easy to load the data structures and build indexes from the
file.
>
> Mi opinion about the future is:
> Create a simple CAD format with a free CAD software, without 3D
> modeling. We have blender to 3D modeling. Autocad and Microstation
> lose the time with modeling utilies. A CAD is a CAD, and a 3D model
> software is a 3D model software.
What do you mean, the CAD format should be 2D?
martin_gnu
>
>
>MicroStation can not use a xml file format because every action in MS
>is written to the design file and they need to search elements fast
>(index).
>Constant update of the design file has an advantage, no data is lost
>in case of a run time error, the disadvantage is that a binary file
>has to be used.
>
edition is very slow in Microstation.
>
>For AutoCAD i think xml is usable, the dwg is read into memory, all
>actions are only done in memory until the dwg is saved. So for AutoCAD
>only the load and save time will increase (dxf like performance). I
>think AutoCAD will not make its document format open/readable, just to
>keep the Open Design Alliance busy.
>
The last day Carl Reed who is the Chief Technology Officer at the Open
Geospatial Consortium talk about XML in this list. He talks us about
XML OGC standards. It seems that XML has a lot of advantages, but it´s
posible use a XML CAD file??. We will open our CAD files in a good
time??. I am using for example glade XML files and it´s open very
fast... But in CAD is posible this velocity??
>
>I think the data structures in wich the data is read are also of
>interest, the performance of a application depends on it.
>For large models you need to use some kind of index to query elements
>in cases you can not use opengl/mesa.
>
Franz Reiter has experience in MESA. His experiences can be useful for
all in this list.
I have used gcad3D using his ascci format and works very fine.
someone can study the Franz Reiter format?
http://groups.google.com/group/open_cad_format/web/open-cad-format
This format can be tested in gcad3d:
http://www.gcad3d.org/gCAD3D.htm#Downloads
We have much more advantages using XML files?? It would be very
important answer this question.
If the answer was YES, then perhaps we can edit the city3D-GML-SVG to
get a XML cad format.
It´s posible 2 CAD format??
1 CAD format for works native in CAD software
1 XML CAD format for exchange files between diferent software.
It´s very crazy thinks about 2 CAD format??
OGC XML files are used like native formats in ESRI, Intergraph or
Smallworld software or only to exchange files.??
In office tools XML is native format, but in that kind of tools they
have a lot of XML files inside to works fine.
>
>What do you mean, the CAD format should be 2D?
>
3D of course, but without rendering, texturing, bones, ilumination,
animations... Autocad and Microstation have modeling utilities in last
versions, but i think that this is not a CAD problem,...
I have used Maya and it´s only for 3D modeling. Buildings
visualizations are made in software like 3DMax importing DXF/DWG
files.
The work for modeling in a CAD is very hard besides the results are
good.
ftp://ftp2.bentley.com/dist/collateral/Web/BI/Cover_Rendering.jpg
I think that Blender is a good choice in open CAD world to that
activities. Blender for engineering is perfect.
Regards.
Franz Reiter
the dxf-format and many others are not so good for the definition of
parametric objects. An example:
you have 2 lines; the intersction-point shall be the center of a circle.
In iges, step and gcad3d you can do that:
Set Point1, 2, 3 and 4 with coords.
Set Line1 = Point1 to Point2, Line2 = Point3 to Point4.
Define Point5 = intersection of Line1, Line2.
If you redefine Point1 all other definitions are OK (parametric).
In dxf i think, you cannot define this parametric dependencies.
The step-format looks like that:
..
#869 = LINE( '', #1612, #1613 );
#1612 = CARTESIAN_POINT( '', ( 0.0, -1.25, 13.0 ) );
#1613 = VECTOR( '', #2336, 1.0 );
#2336 = DIRECTION( '', ( 0.0, 0.0, 1.0 ) );
..
here the line is trimmed:
#449 = TRIMMED_CURVE( '', #869, ( CARTESIAN_POINT( #870 ) ), (
CARTESIAN_POINT( #871 ) ), .T., .UNSPECIFIED. );
Usually cad-systems operate with the binary objects; the native format is
binary.
If you want to use a ascii-readable native format you also have to translate
each ascii-object into a binary object (for fast usage and computations you
have to put the objects into tables (a database)).
For the display of modeldata with OpenGl (Mesa or Hardwareaccelerated) you
have to:
- break the object into viewable pieces (polygons, triangles ..),
- hand it over to OpenGL, keep its ID in a displayList.
For modfications of entities:
If your native format is binary, you have to extract all parameters from the
binary object.
If you work with the primary modeldata in ascii, the parameters are present
immediaty; after modification the text must be transformed again into the
binary obect ....
Translation is a slow process (interpreter) !
If you interchange cad-data lets say from step to dxf you strip off all
parametric dependencies.
Franz
martin_gnu
Masterful lesson in CAD hehe
Besides gcad3d format is a pseudo-scripting format. It´s much more
than a simple format.
I really believe that a native gcad format is necessary for all CADs,
but perhaps a exchange XML format was useful too. With a XML format
would be easy create XSLT scripts to conversions between SVG, city3D,
GML...
The gcad3d format is almost complete, and we can to see it working in
a real software like gcad3d. This format is so quick than DWG in
Autocad in my tests.
the name can be:
.gcad/.gcaz
or:
.oca/.ocaz
Votings for the name...
Gertwin
> but perhaps a exchange XML format was useful too. With a XML format
> would be easy create XSLT scripts to conversions between SVG, city3D,
> GML...
Ok lets start by reading the document describing the gcad format.
> The gcad3d format is almost complete, and we can to see it working in
> a real software like gcad3d. This format is so quick than DWG in
> Autocad in my tests.
>
> the name can be:
> .gcad/.gcaz
> or:
> .oca/.ocaz
>
> Votings for the name...
I vote for .oca/.ocaz, i always thought the 'g' stands for gtk?
Gertwin
Thanasis
On Aug 29, 7:00 pm, "Martín RV (OPENGeoMap)" <mar...@opengeomap.org>
wrote:
> A question for you. dont´t you see the pythonCAD?http://www.pythoncad.org/
Of course I have seen pythoncad. However ThanCad uses Tkinter, it has
hierarchical layers and it tries to be as close to AutoCad as
possible. I hope that the 2 projects will share code in the future.
martin_gnu
>
> Ok lets start by reading the document describing the gcad format.
It´s very easy to learn:
http://groups.google.com/group/open_cad_format/web/open-cad-format
But you can play a little with gcad3D to learn. gcad3D is a little
dificult to learn but it´s almost complete in primitives (lines,
circles, splines, surfaces,...) and works fine.
I hope make several surveying files in this format to study
posibilities.
gcad3d have a option very interesting to learn. In the main window you
can see VWR/CAD/MAN radio buttons. In the MAN you can see like open
cad format works step by step. GCAD3d it´s full of samples to study
step by step.
We hope new informations from Franz about databases and MESA to study
more posibilities in the format. We have to talk about layers, colors,
line styles... I have some questions about this primitives in gcad.
For example. Autocad only have layers, but Microstation have a system
very easy to implement sublayers like this:
sub1.layer0
sub1.layer1
sub2.layer0
sub2.layer0
We can use a metacharacter like "." or other to find sublayers. This
the system of Microstation and i think that is very intelligent.
We can think in oca/gcad (votings!) like the model space, but inside
the ocaz/gcaz (votings!) we can put SVG files like paper space. In the
future will be very easy work with SVG in GTK(inskape) or
Qt(Karbon14). It´s posible have very complex widgets to work in SVG in
the future. I think that SVG for plotting can be a perfect opcion in
the future for all kind of plotters. Besides nowadays conversions from
SVG to PDF are very matures.
Then:
oca/gcad (model space)
ocaz/gcaz (model space,SVG1,SVG2,SVG3,...)
Regards.
Standards Guy
Thanks for the thoughtful response.
I would like to be very clear that the OGC Geography Markup Language
(GML) is content model independent and vendor product/format neutral.
It is not like an ESRI shape file or a Autocad DXF file, which are
vendor specific. However, one could encode the information content
contained in a shape file or DXF file as a GML application schema.
Further, one can integrate schemas from other information communities.
For example, CityGML uses both GML and X3D schemas. The X3D schemas
are used to encode the information related to 3d texturing and light
sources.
Regards
Carl
OGC
On Sep 12, 2:24 am, martin_gnu <opengeo...@gmail.com> wrote:
> >MicroStation can not use a xml file format because every action in MS
> >is written to the design file and they need to search elements fast
> >(index).
> >Constant update of the design file has an advantage, no data is lost
> >in case of a run time error, the disadvantage is that a binary file
> >has to be used.
>
> This kind of things in Microstation don´t like to me. Real time 3d
> edition is very slow in Microstation.
>
>
>
> >For AutoCAD i think xml is usable, the dwg is read into memory, all
> >actions are only done in memory until the dwg is saved. So for AutoCAD
> >only the load and save time will increase (dxf like performance). I
> >think AutoCAD will not make its document format open/readable, just to
> >keep the Open Design Alliance busy.
>
> The last day Carl Reed who is the Chief Technology Officer at the Open
> Geospatial Consortium talk about XML in this list. He talks us about
> XMLOGCstandards. It seems that XML has a lot of advantages, but it´s
> posible use a XML CAD file??. We will open our CAD files in a good
> time??. I am using for example glade XML files and it´s open very
> fast... But in CAD is posible this velocity??
>
>
>
> >I think the data structures in wich the data is read are also of
> >interest, the performance of a application depends on it.
> >For large models you need to use some kind of index to query elements
> >in cases you can not use opengl/mesa.
>
> Franz Reiter has experience in MESA. His experiences can be useful for
> all in this list.
> I have used gcad3D using his ascci format and works very fine.
> someone can study the Franz Reiter format?http://groups.google.com/group/open_cad_format/web/open-cad-format
> This format can be tested in gcad3d:http://www.gcad3d.org/gCAD3D.htm#Downloads
> We have much more advantages using XML files?? It would be very
> important answer this question.
> If the answer was YES, then perhaps we can edit the city3D-GML-SVG to
> get a XML cad format.
>
> It´s posible 2 CAD format??
> 1 CAD format for works native in CAD software
> 1 XML CAD format for exchange files between diferent software.
>
> It´s very crazy thinks about 2 CAD format??OGCXML files are used like native formats in ESRI, Intergraph or
> Smallworld software or only to exchange files.??
>
> In office tools XML is native format, but in that kind of tools they
> have a lot of XML files inside to works fine.
>
>
>
> >What do you mean, the CAD format should be 2D?
>
> 3D of course, but without rendering, texturing, bones, ilumination,
> animations... Autocad and Microstation have modeling utilities in last
> versions, but i think that this is not a CAD problem,...
> I have used Maya and it´s only for 3D modeling. Buildings
> visualizations are made in software like 3DMax importing DXF/DWG
> files.
> The work for modeling in a CAD is very hard besides the results are
> good.ftp://ftp2.bentley.com/dist/collateral/Web/BI/Cover_Rendering.jpg
martin_gnu
Hello:
> It is not like an ESRI shape file or a Autocad DXF file, which are
> vendor specific. However, one could encode the information content
> contained in a shape file or DXF file as a GML application schema.
> Further, one can integrate schemas from other information communities.
> For example, CityGML uses both GML and X3D schemas. The X3D schemas
> are used to encode the information related to 3d texturing and light
> sources.
But what do you recommend us?
XML like exchange format not?
XML is good for big files?? There are studies about problems with
this???
By now Blender isn´t use web3d.org standards like native format.
Blender works with this formats:
Import all comercial files and COLLADA
Export all comercial files and COLLADA and X3D,
But blender use a native file to work. It´s the same that Franz Reiter
talk about.
http://en.wikipedia.org/wiki/COLLADA (for video games)
http://en.wikipedia.org/wiki/X3D (succesor fo WRML)
There a X3D CAD especification, perhaps we have here a new exchange
file... I have several books of XML in house i need study a lot hehe.
http://www.web3d.org/x3d/workgroups/cad/
This last link is very interesting for all. Perhaps is interesting
join to this group in some way or talk with them...
It´s obvious that it´s not necessary build a new XML file because we
have already.
According to blender in 3d modeling, a CAD can be like this:
oca/gcad like native format.
X3D CAD like exchange format.
DXF like exchange format.
openDGN, openDWG like exchange format.
There is good discussion about STEP-X3D CAD here:
https://www.email-lists.org/pipermail/freearchitecture/2006-May/000074.html
I send a mail to this free Architecture list to join to
open_cad_format iniciative.
Thanks for the information Carl. It´s very useful for us.
Regards.