I have a LiDAR file with contours and other features. How do I use Autocad to determine xyz values? First LiDAR file for me.
thanks in advance.
Warren Ward, CO PLS
- Have a nice day! Or, may your monument prevail over some guy's touchscreen.
If you've received contours then you don't have the actual Lidar data. Typically Lidar is delivered as a .las file or a coordinate text file. What other features do you mean - linework and symbols or something else?
You've opened it in AutoCAD already?
Using ID command with Autosnap will tell you the co-ordinate of the point.
eg use "nea" autosnap to snap to a contour line.
You will then see if the drawing is in true 3D or flat 2D.
On a side note / user tip
Carlson does have a useful way to bring Lidar data. As a text file, importing all those points into CAD is usually very demanding on computer resources.
The trick (it's been a while but I think that how it goes) is to:
- In CAD, create an inclusive boundary of the area in which you want Lidar data.
- Call the Triangulation and Contour program (command tri)
- Make sure to click the box Use Inclusion/Exclusion areas
- Click off the box draw tri-faces and tri-lines (demanding on computer resources)
- Click off contours for now too, you can draw later with Contour from tin
- In the fourth tab, under selection, you can choose an external ASCII file. This file does not required to be brought in the program.
Run the program, select your inclusive boundary and your external LIDAR text file; the tri surface is created as a proprietary tin file but not drawn. Then you can do your thing with the surface file in your area of interest.
The positive aspect of this method is that the tens of thousands of points that make a lidar text file are never brought in the CAD environment. Same with the 3x tens of thousands of 3d segments that tri-faces and/or tri-lines generated from all those points.
Very good trick. Thank you.
Another suggestion (one that I'd typically use only with point-only LIDAR data) is the "Simplify Surface" toggle found on the Triangulate tab:
In this example, I'm instructing the Triangulate & Contour routine to remove redundant triangles from the model if the resulting change doesn't alter the model by more than 0.05' vertically.
thanks to all - I'm up and running - this board steps up as always.
Warren Ward, CO PLS
- Have a nice day! Or, may your monument prevail over some guy's touchscreen.
