Trying to use the data from map in description and export contours with height value to create a site in Rhino 7

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James Bell

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Apr 20, 2023, 8:08:00 PM4/20/23
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https://data.cityofsydney.nsw.gov.au/datasets/80e5e6f05d274ec4bffa6b182f3474c4_0/explore?location=-33.889283%2C151.203840%2C14.12

I am trying to create contours with height values from this map, and export it to rhino to create a site for a univeristy project. I have followed a few YouTube tutorials, with no luck. I have tried to use the GRASS plugin, and can see the contours have height values, just having trouble translating it.

Any help would be very very appreciated.

James

box...@iinet.net.au

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Apr 20, 2023, 8:18:06 PM4/20/23
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Hi James,

 

The link has datasets to download which I assume are contours. Are you just trying to label the contours?

 

What are you up to these days?

 

Cheers Grant

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James Bell

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Apr 20, 2023, 8:26:30 PM4/20/23
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Hi Grant,

Thanks for getting back to me. I am trying to assigns z--values to the contours so I can create a mesh of the site in rhino. I saw in the attribute table that the contours have height data, it’s just getting it into rhino which is hard.

I am currently studying architecture at UTS!

James

box...@iinet.net.au

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Apr 20, 2023, 9:01:49 PM4/20/23
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You may need to import the shape file elevation data as a LineZ file so that it records the lines as 3D. I don’t know Rhino so can’t help in that direction.

Juan Fernando Berrío

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Apr 20, 2023, 9:18:28 PM4/20/23
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Hello James,

You're lucky - this question was asked in the past and I think a solution was found.  Have a look a the conversation and let us know if it covers what you need.

https://groups.google.com/g/australian-qgis-user-group/c/bncg38DEJbw

Cheers,
Juan


Luke Kirkwood

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Apr 20, 2023, 9:23:20 PM4/20/23
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Out of interest, does anyone know if you can use the geometry feature of the export functions in QGIS to correctly include the z-dimension to an exported DXF and thereby reduce the number of steps needed in the prior solution linked?

image.png

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box...@iinet.net.au

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Apr 20, 2023, 9:43:51 PM4/20/23
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When you export the 3D polygon shapes for example, use the Layer Option and POLYGONZ. Try that.

 

Cheers Grant

 

 

From: australian-qg...@googlegroups.com <australian-qg...@googlegroups.com> On Behalf Of Luke Kirkwood
Sent: Friday, April 21, 2023 9:23 AM
To: australian-qg...@googlegroups.com
Subject: Re: [Aus-NZ-QGIS-group] Trying to use the data from map in description and export contours with height value to create a site in Rhino 7

 

Out of interest, does anyone know if you can use the geometry feature of the export functions in QGIS to correctly include the z-dimension to an exported DXF and thereby reduce the number of steps needed in the prior solution linked?

 

Luke Kirkwood

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Apr 20, 2023, 11:21:08 PM4/20/23
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Awesome, thanks for that Maia.

On Fri, 21 Apr 2023 at 12:06, Maia Williams <ma...@maia.id.au> wrote:

Hi James and Luke,

Luke - unfortunately not. You need to write the elevation (attribute) values to Z values (using the Set Z value tool) and then when exporting to DXF also be sure to tick the Geometry>Include Z-dimension and specify LineString as the geometry type. The 'Include Z-dimension' can't read the Z value directly from an attribute field... so you need that middle step which converts the dataset to a Line (MultiLineStringZ) geometry type.

James - hopefully this work flow will do the trick for you. You were on the right track with the GRASS connection. There is a GRASS tool called V.to.3D which does the same as Set Z values. Also don't use the Import/Export>Export Project to DXF method for data with z values - the z values aren't retained in this conversion. Just use the Export>Save Features As method with settings as above.

Cheers,

Maia

Maia Williams

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Apr 28, 2023, 5:49:18 PM4/28/23
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Hi James and Luke,

Luke - unfortunately not. You need to write the elevation (attribute) values to Z values (using the Set Z value tool) and then when exporting to DXF also be sure to tick the Geometry>Include Z-dimension and specify LineString as the geometry type. The 'Include Z-dimension' can't read the Z value directly from an attribute field... so you need that middle step which converts the dataset to a Line (MultiLineStringZ) geometry type.

James - hopefully this work flow will do the trick for you. You were on the right track with the GRASS connection. There is a GRASS tool called V.to.3D which does the same as Set Z values. Also don't use the Import/Export>Export Project to DXF method for data with z values - the z values aren't retained in this conversion. Just use the Export>Save Features As method with settings as above.

Cheers,

Maia


On 2023-04-21 09:23, Luke Kirkwood wrote:

James Bell

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Apr 28, 2023, 5:49:18 PM4/28/23
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Hi Jaun,

Thanks for linking that post. I followed it step by step, and still when i open the dxf file in rhino, all the z-values are set to 0....

Am a bit stuck, could it be something with the data I am using?

James

James Bell

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Apr 29, 2023, 3:38:45 AM4/29/23
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Hi Maia,

Thanks for gettig back to me. I think I hve worked out what is going on. I think the contours, and height values are in different units. 

When I open the file in rhino, the contours are only millimetres long, where as the vertil distance between them is in metres. Is there a way to resovel that? 

Thanks,
James

Maia Williams

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Apr 29, 2023, 3:38:45 AM4/29/23
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Hi James,

I missed this email when you sent it last week. I'm sure you've found a work around by now. But in case you're still needing this data in Rhino, I've converted the linked contour dataset to check it works. The version I converted to dxf looks good in AutoCAD, with elevation values showing. I don't have Rhino installed just now so I can't test it there but I'm sure if it's good in AutoCAD then it'll be fine in Rhino.

The dxf is here if you want it: https://drive.google.com/drive/folders/1nuBrg_hVCI_Y-GXd14IVyyhnWBM6l3zE?usp=share_link

The steps were:

  • Started with the shapefile version of the data.
  • Reprojected to GDA2020 MGA56 because you would never bring WGS 84 data into AutoCAD/Rhino (you need your data in m or mm, not degrees).
  • Run the Set Z Values tool.
  • Save as dxf being sure to tick 'Include z dimension'.

In AutoCAD the data looks like below. In plan view and in elevation (showing z values definitely in the data).


I have a set of notes covering QGIS workflows used by architects/landscape architects that I use for teaching (mainly about getting data into CAD correctly, like your situation here). I'm happy to share if you're interested.

Cheers,
Maia

Maia Williams

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Apr 29, 2023, 11:50:23 PM4/29/23
to australian-qg...@googlegroups.com, James Bell

Hi James,

I've just added your latest email to my reply from yesterday (below).

Did you definitely reproject the data in QGIS before saving to dxf? If you don't do that step then x/y and z will be in different units. If you reproject to GDA2020 MGA56 (or whatever projected coordinate system you're using) then everything will be in metres in the dxf.



If you've done that reprojection step then the issue lies in your CAD/Rhino drawing setup. Have you set your drawing units correctly?

  • If you've just opened the contour dxf in a new AutoCAD/Rhino drawing it will use whatever your default units are (perhaps mm in your case). So you'll have to use DWGUNITS to change the drawing units to metres and choose not to rescale the existing data when you do that. Then everything (X/Y and Z) will be in metres.

  • If you're copying the contour data into an existing drawing (that's in mm) then you'll need to rescale your contours to mm before copying the layer into your main drawing. First open the contours dxf then use DWGUNITS make sure your drawing units are set to mm. Choose to rescale your drawing. Then COPYBASE this contour layer into your main drawing and everything should overlay* and will be in mm (X/Y and Z). You can do some distance checks against the data in QGIS.



I don't have Rhino on hand to check for the equivalent commands but I'm sure you can do the same from there.

*It will all overlay if your main drawing is also in GDA2020 MGA56.

If you need more CAD/Rhino help feel free to email me directly because it's a bit off-topic for this mailing list at that point :)

Good luck!
Maia


 

 

 


Hi Maia,

Thanks for gettig back to me. I think I hve worked out what is going on. I think the contours, and height values are in different units. 

When I open the file in rhino, the contours are only millimetres long, where as the vertil distance between them is in metres. Is there a way to resovel that? 

Thanks,
James


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