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Best Way to Import a Surface

Message 1 of 4
803 Views, 3 Replies

Best Way to Import a Surface

In the projects I am currently working on I am going to spatial data download and downloading the DEM files for my area. I then go to toolspace and insert my DEMs through the DEM files folder. I have found though that it slows my drawing down tremendously and even causes it to crash at times. It honestly makes the drawing almost unusable at times- I use the boundary feature and data clip it to as small as possible but even then it causes so many issues. I looked into downloading the contour data as a shapefile from but have found that the information is not near as accurate. Just wanted to see what others are doing and what the best way to import surfaces is? 

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Message 2 of 4
in reply to: sarah_karan

I typically use a 3rd party program to trim dems down. Global Mapper is the one we purchased, but i understand there are free ones available. I also create an empty surface and then add the dem data as opposed to creating one from a dem. Though I'm not sure that has much effect on speed.

Message 3 of 4
in reply to: cwr-pae

Thanks for the advice about trimming outside of C3D, that could help. I believe that is also how I insert the DEMs as I right-click on Surfaces and click create Surface.

Message 4 of 4
in reply to: sarah_karan

Hi Sarah,
DEM's are a derivitive product, once removed from the original LiDAR data.
LAS or LAZ files can either be run through ReCap or you can use DotSoft's excellent free >>>Lidar Tools<<<.
As you import a ReCap RCS file into Civil 3D, there is a step which allows you to decimate the points to any spacing, e.g., 1mm, 1 meter, etc. That way you can adjust the surface size to make sure it's under 2 million points, and you won't create the dreaded MMS file which is a death sentence for a surface.

Dave Stoll
Las Vegas, Nevada


NVIDIA Quadro P5000 16GB
Windows 10 Pro 64 / Civil 3D 2024

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