Topographical Survey dwg import issue

[Hugh Chapman]

We regularly encounter the following issue when importing topos -

 

Spot heights in 3D topo surveys we recieve are generally represented by block instances. These are generally simple crosses made from two lines -

 

 

We can open 3D topo surveys in Autocad/Rhino and confirm that these spot heights have the correct z-value (15.75m for the example above).

 

But when we import the 3D topo dwg into Vectorworks, VW converts these blocks into symbols which are all at z=0. i.e. VW unhelpfully loses the z-values of all the spot heights when importing 3D topos. I can't find any import setting to avoid this 'flattening' of the spot elevations. 

 

Our workaround for this is to open 3D topos in Autocad/Rhino, update the spot height block instances to contain only points, then explode the blocks. Then when we import into VW we can tell VW to convert these points to 3D Loci, thus retaining the z-values of the spot heights.

 

We want these spot heights to generate a site model.

 

Am I missing something with this? Is there a better workaround for this in VW itself..?

 

Thanks

Edited April 1 by Hugh Chapman

[Katarina Ollikainen]

@Hugh Chapman, can you post or send me an example of the survey so I can have a look - if there is 3D information, you should be able to retrieve it.

[HebHeb]

You can import the DWG twice — this is usually how I handle it.

• Import it once as 2D/3D Object Conversion for the best 2D appearance.
• Import it a second time as 3D Objects only.

With the second import, blocks that contain 3D information should be placed at the correct Z height.

If I remember correctly, Vectorworks changed this behavior sometime between 2020 and 2022. In older versions, using the 2D/3D import option converted the blocks into symbols and preserved the correct Z elevation for each instance. In current versions, they tend to remain flat instead...

Sometimes the imported objects also have a record attached that stores the correct Z values. If so, you can use that record field to set the Z height accordingly - in that case: no need for a 2nd "3D only" import.

conversion option is found in advanced dwg import settings:

[Katarina Ollikainen]

 

Yes, the double import is the best way to resolve this. 

Importing it as only 3D gives you access to all the 3D data in the file in a format you can use, and a second import for the 2D gives you the top plan.

Here is a recording on how to do it.

 

[Hugh Chapman]

many thanks for the explanations @HebHeb & @Katarina Ollikainen - problem solved!