export surface to dem *.tiff

[briandH3WE9]

attempting to export a 80 acre surface to dem for use in ICPR (streamline technologies model) and the surface model export dies on the vine... it runs for 48 hours and hangs at about 75%. Anyone know what the limits are for dem export? I am using a 5 foot grid on the export. Is there a way to tweak the surface to make it more easily exportable? 

I would like some help on this one. Next step would be to create a gird and make 4 independent surfaces for each quadrant of my site to make the export size 1/4 of the original surface. It would seam that many sites are larger than 80 acres, yet I am having issues....

Thanks for the help on this one...

[AllenJessup]

I don't know the specific limit. However. Is it necessary to have a 5' grid? I know that if the data can be captured we tend to want to use it. I tend to over extract/analyze data myself.

[briandH3WE9]

I typically use lidar data which is at one meter or a 3 foot grid, thus I thought a 5 foot grid should work with ease. On smaller sites I typically use the one foot grid on existing surfaces and/or 1/2 foot grid on proposed surfaces to get the detail that I need for the hydraulic modeling. I have never had a problem util this site/file. I have done 60 acre sites without issue, it has just taken over night or maybe 24 hours to export. This site does not want to export without hanging up.

Thanks,

[ChicagoLooper]

Are you exporting to dem or tif format? Experiment by increasing the grid spacing to 20 feet. What happens? Increase spacing to 100 feet. What happens?

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If possible, upload a screen shot of the Export Surface to DEM dialog window?

[briandH3WE9 · Accepted solution]

I did find a work around...

First, my surface was created by using survey points and GIS Lidar Data Contours (to fill in the gaps). I also added in flood plain and water elevation contours. Long story short if I use the DEM export to *.tiff with a grid of 100 then it works in about an hour.

I also tried to simplify the surface on the surface edit options. Did not make any difference.

Here is how I solved the issue.

I created a point group called grid and then I created points on a grid (3 foot grid) automatically on the surface elevation. It created a ton of points... over 25k

I then exported the point group to a file.

I then created a new drawing and imported the points from the point group.

I then created a new surface from the point group.

I then exported the DEM to *.tiff and it worked fine. It took about 10 minutes to export 80 acres with a grid spacing of one foot.

I think the original issue is with the contour data in the original surface. 

I have attached the finished product screen shot from within the modeling software where the dem was imported.

As a note: I also tried to export the surface to landXML and then import into a new drawing, but it had the same issues... and would not DEM export with a grid set to five feet...

[AllenJessup]

Glad you solved it. Thanks for posting.

[briandH3WE9 · Accepted solution]

All,

After more episodes of this happening with large sites (>20 acres), I found another way to make this work. I typically use the surfaces for ICPR (Streamworks) for storm water modeling, thus I need these surfaces in a DEM TIFF format. 

Here is what I do now which is easier. I simply export the surface to a LandXML file.  Then in a new, empty, blank, clean file, I import the LandXML file and set the contours intervals to 1/2 foot min. and then it will export to DEM TIFF as normal.

Hope this helps.

[lim.wendy]

Hi Brian,

Thank you so much for sharing this solution! I'm glad that exporting the surface to a LandXML file first and then working from a clean file helped with the DEM TIFF export. I’ve also marked your response as the ‘Answer’ so others facing similar issues can find it easily, as posts with accepted solutions tend to have higher visibility.

We appreciate your contribution to the community!