Jump to content
JohnAthayde

DTM > Site Model directly?

Recommended Posts

I have four DWGs from Albemarle County's (VA) extensive GIS system. Two different grid blocks, mass points and breaklines for each. I can bring them into a file and they show at elevation when the view is rotated. I can get them all onto the same design layer, but how does one use these together in creating a site model? I could generate something with just masspoints but I'm betting the breaklines are there for a reason. In trying a test, it didn't seem to comprehend the data by default.

 

I also have the 4' topos and a site survey of a much smaller area with stakes for elevation points that were measured by the survey crew. They didn't do a lot of the paddocks which is our focus in this project, so trying to get better than 4' data before I just go shoot it myself. Screenshot of area in question attached before I merged them to one design layer (hence the left being grayed out)

 

VW Designer 2017 if it matters.

Screenshot_2017-12-28_22_31_37.png

Edited by JohnAthayde

Share this post


Link to post

Are the break lines 3d with correct z ranges? loci correct z?  In a new blank vwx file try making a DTM by selecting all the 3d loci and the 3d break lines - or just a small test area-  then Create Site Model. Might be what you need with no further horsing around. If the break lines are not producing proper DTM then try decomposing them which should “explode” each 3d poly into a bunch of segments each at correct z. Or at least each segment will yield an average z over a very short distance. 

 

-B

Share this post


Link to post

John,

I'm going to back up a bit here. I have worked extensively in the Great Commonwealth of Virginia and have some experience in counties near you. How did you come to get AutoCAD files from the County GIS office? I might be mistaken but I think that you may have better luck if you request and import Shapefiles of the same data set as they may come with contours rather than points and breaklines as you have shown. If you have a contact in their GIS department ask if they can't give you Shapefiles and see how that turns out.

Best of luck.

Share this post


Link to post
11 hours ago, rowbear97 said:

John,

I'm going to back up a bit here. I have worked extensively in the Great Commonwealth of Virginia and have some experience in counties near you. How did you come to get AutoCAD files from the County GIS office? I might be mistaken but I think that you may have better luck if you request and import Shapefiles of the same data set as they may come with contours rather than points and breaklines as you have shown. If you have a contact in their GIS department ask if they can't give you Shapefiles and see how that turns out.

Best of luck.

 

Robert —

 

Albemarle publishes their GIS online. Here's the Elevation options:

https://www.albemarle.org/department.asp?department=gds&relpage=3914#Elevation

 

There's variosu things there (Shapefiles, DEM, etc) that I'm quite unfamiliar with. I'll see if I can import the shapefile for the DTM and if that gives me a better result when running a site model.

 

On 12/29/2017 at 10:18 AM, J. Wallace said:

@JohnAthaydeyou might want to check out this post...

 

 

J. —

 

Thanks! I am familiar with LIDAR from the vfx world, but that's typically used scanning elevations, didn't think about it from drone! I seem to have hit some of the similar issues you discussed there. 

 

On 12/29/2017 at 7:28 PM, Benson Shaw said:

Are the break lines 3d with correct z ranges? loci correct z?  In a new blank vwx file try making a DTM by selecting all the 3d loci and the 3d break lines - or just a small test area-  then Create Site Model. Might be what you need with no further horsing around. If the break lines are not producing proper DTM then try decomposing them which should “explode” each 3d poly into a bunch of segments each at correct z. Or at least each segment will yield an average z over a very short distance. 

 

-B

 

Benson —

 

I don't know if they're correct. I'm doing a 3d import of the DWGs, but lines and loci are from different files. they line up correct in the X and Y, however. There's another DWG of 4' contours and those are exploded lines that I've been slowly selecting and doing Modify > Compose to try and build something that way.

 

 

Share this post


Link to post

@JohnAthaydeif the dwg is not working easily for you, try the shapefiles (.shp). These are GIS files - georeferenced geometry, usually with a single type of object per file usually indicated in the file name, eg 4’ contours, or curbedge, or parcels, etc. Download the relevant shapefile and note the georef format (eg plat carrie) ,  open a new vwx file with appropriate layer scale, import the  .shp opting for the corresponding geo format choice in the import dialog. You can use the objects as is, or copy/move them as needed, but these geo ref objects may be a long way from your drawing origin, and may also include a vast area outside your area of interest. Therefore it’s often useful to reference this file into your project file via a design layer viewport.  Post back for more help as needed.

 

-B

  • Like 1

Share this post


Link to post
On 1/3/2018 at 9:34 PM, JohnAthayde said:

 

Robert —

 

Albemarle publishes their GIS online. Here's the Elevation options:

https://www.albemarle.org/department.asp?department=gds&relpage=3914#Elevation

 

There's variosu things there (Shapefiles, DEM, etc) that I'm quite unfamiliar with. I'll see if I can import the shapefile for the DTM and if that gives me a better result when running a site model.

 

 

J. —

 

Thanks! I am familiar with LIDAR from the vfx world, but that's typically used scanning elevations, didn't think about it from drone! I seem to have hit some of the similar issues you discussed there. 

 

 

Benson —

 

I don't know if they're correct. I'm doing a 3d import of the DWGs, but lines and loci are from different files. they line up correct in the X and Y, however. There's another DWG of 4' contours and those are exploded lines that I've been slowly selecting and doing Modify > Compose to try and build something that way.

 

 

John,

Under Y2013 I chose I've successfully downloaded 'Topography - 2 foot Contour Interval format Shapefile. Start a blank file create a class for contours. Go to File<Import<Import Shapefile. Select the downloaded tile (it is broken down into a grid I've tested 059 and 060) and click Open. Change to Design layer or one of your own choosing or it will create one from the file. Select the created class for contours and click Ok. Landmark will take it from there. Tile 60 would appear to be Ivy and 250 interchange and a good part of Campus including the Darden School. Make sure you change you plan scale to 1"=100'. Also change your origin as these tiles seem to be set to the state grid, by going to Tools<Origin<Center Drawing on Internal Origin. This will keep the coordinates the same while making modeling more efficient. If you continue to have issues you may want to change the origin entirely keeping in mind that this will make exporting or sharing back to the state plane very difficult. At this point you might want to change your view to Front to confirm all the contours are at elevations (this is also good to do to check for anomalies in the data). Check for groups and un-group these objects, selecting to attach records to these items. The contours will not be all connected, but if you are making a digital terrain model it will not matter. You might want to simplify the 3D polys. Select all 3D polygons and create you site model. Depending on your needs for planning purposes or other do choose wisely as just modeling tile 59 (Ivy) at 2' contour interval took my machine some time to complete. Best of luck.

ivy model.jpeg

  • Like 1

Share this post


Link to post
7 hours ago, rowbear97 said:

Tools<Origin<Center Drawing on Internal Origin

I thought this moved all the geometry and therefore coordinates would change from real world to something nearer xyz =0. And also if subsequent layers have different extents they would center on origin differently. Will have to learn more about this feature. 

 

-B

Edited by Benson Shaw

Share this post


Link to post

@rowbear97 Wow. thank you so much. I'll pull those files (the site borders a boundary of one DTM square) and run it. I've got a 2008 MacPro 8 core with 32G of ram, so I'd expect similar, if not slightly slower, results. Will report back with success or failures :)

 

Thank you again!

Share this post


Link to post
On 1/18/2018 at 7:17 AM, JohnAthayde said:

@rowbear97 Wow. thank you so much. I'll pull those files (the site borders a boundary of one DTM square) and run it. I've got a 2008 MacPro 8 core with 32G of ram, so I'd expect similar, if not slightly slower, results. Will report back with success or failures :)

 

Thank you again!

@JohnAthaydedid you get this to work to your satisfaction?

Share this post


Link to post

This is weird. Stumbling upon other users who are also doing work in the County. Had no idea you guys were out there. Even better, with excellent advice on how to battle thru DTM creation using county gis data. Nice DTM  rowbear.

Share this post


Link to post

@jnr I'm available for assistance. Only familiar with the area as we lived in Richmond for 8 years and my wife went to Darden for her MBA. Glad to help.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

 

7150 Riverwood Drive, Columbia, Maryland 21046, USA   |   Contact Us:   410-290-5114

 

© 2018 Vectorworks, Inc. All Rights Reserved. Vectorworks, Inc. is part of the Nemetschek Group.

×