3D Surface Creation Z-coordinates are Stuck in Meters

[CColozza]

There's got to be something I'm doing wrong here, and perhaps the issue is with the PVcase add-in I'm using; but hopefully not. What I'm trying to do is take a field of elevation points (created by PVcase) and use the "Create 3D Surface from points" tool to create a rasterized .TIF terrain file. I believe the data imported elevation data comes directly from Google Earth. In theory, just about any group of points with elevation should work, they don't have to come specifically from PVcase.

When I go and open up the tool, I get the screen below:

I'm using the OH83-SF coordinate system in my drawing and the drawing units are set to feet. As far as I know, all PVcase units are set to feet as well. However, notice that the "Z-Unit" says its in meters. I want to change that to feet to match the X-Y units of the drawing. Selecting the cloud of elevation points on my drawing does nothing to unlock this drop-down box. If I choose to ignore this, set the "Coordinate System Assignment" to OH83-SF, and have AutoCAD create the 3D surface, I get the picture below:

Notice that the purple 3D surface has a much higher elevation than the white data points it was created from. To me, this looks like it's using meters instead of feet, as the purple surface appears to roughly be 3x higher than the white points. I've created demonstration drawings and attached them; the one ending in "With Surface" has the purple 3D surface already created while the other file does not (in case someone wanted to troubleshoot and compare). You'll notice that the 3D surface is much more exaggerated than the white elevation points, also indicating the elevation is in meters and not feet.

Is there something I'm clearly missing in a setting somewhere? How can I change the Z-Units to feet? Everything that I can think to check within the drawing has units that aren't in meters.

[Pointdump]

Hi Charlie,
You've got to grab a point file first before you can change the Z units.
Dave

[CColozza]

This is the screenshot I get when I select the data points within the drawing; I don't have any external data in a CSV to import, I only have what's already baked into the example DWG. As you can see, I've selected all of the points but the Z-unit remains grayed out.

[Pointdump]

Charlie,
Both "Select format:" and "Z-Unit:" only apply if you are using an exterior point file.
Dave

[CColozza]

Dave,

As this workflow is representative of several other projects I'm working on, I don't ever have an external CSV file to import with elevation data. All I've got to work with are the dots that are imported from PVcase, which aren't available as a separate file, it's a built-in AutoCAD add-in. My question now boils down to:

1) How can I export the topographic elevation points already in the drawing into a CSV so that I can then re-import it and tell AutoCAD to use feet instead of meters when Creating a 3D Surface?
2) How can I use the points already within the drawing to properly work with the Create 3D Surface Tool so the Z-units are in feet and not meters?

Charlie

[ChicagoLooper]

Hi @CColozza 

Based on your image and the uploaded dwg's in Post #1, the purple points that appear to be floating in midair seem OK. It's the STUFF below--they look like they're not accurately drawn. They look like they're at sea level and not at their correct elevation.  

 Would it be possible to upload the raster named 1341 points.tif so the surface elevations can be evaluated?

BTW, regardless of what 's grayed out or not grayed out, the raster elevation units cannot be changed from feet to meters or meters to feet--those units were established by the original author when the raster was created. Your raster's units were in FEET, not meters.

Do not confuse changing the units of an elevation label with changing the units of a surface. For example, if a 'point' on a surface is 1000-ft above mean sea level then the label will display 1000. If you change the units in the label from feet to meters, then the label will now display 304.8 meters. (1000 feet = 304.8 meters.) It will not raise or lower the surface, it will only change the label's units.

[CColozza]

Attached is the .TIF surface file from the drawings I attached in the first post.

[Pointdump]

Charlie,
"How can I export the topographic elevation points already in the drawing into a CSV..."?
Use Data Extraction
"How can I use the points already within the drawing..."?
The AutoCAD points in your drawing are in Feet units. If those elevations are not correct, then blame your data.

Dave

[Pointdump]

Charlie,
I went to OGRIP's site where they have tons of elevation data which agrees with your AutoCAD Point elevations.
>>>OGRIP Data Downloads<<<
Dave