I have seen a particular terrain model issue crop up for several users. I already know what the fix is; but I want to understand how this keeps happening, and to try to prevent it.
We are using Power GEOPAK SS3 for the time being, version 08.11.09.722.
I have a DGN with an overpass. The bridge deck lines are included in the terrain model, but are marked as "do not use". The points making up the line are also marked "do not use". The terrain triangles are clearly using some of the points on this line as triangle vertices (but not all). I see no difference in the data for points which are being used and those not being used.
I can find no combination of locking/unlocking the terrain, activating/deactivation survey processing rules which makes this terrain act "live". The only thing that works properly is drawing a linestring around part of this deck, and adding to the terrain as a "hole". The triangles correctly shift to show this hole. Triangles outside of this hole are still where they were, either correctly on the ground or incorrectly up on the deck. Triangles inside the hole are correctly removed.
Changing the deck line to a "breakline" instead of "do not use" adds even more triangle vertices, which is based on our stroking tolerance setting. Changing back to "do not use" merely reverts to the previous incorrect terrain.
There are no underlying lines or points at these locations. All levels are turned on. All field book data is being shown, both "all point features" and "all linear features" checked "on".
Since an exterior clip boundary has already been created, deleting the terrain model and creating a new one from the field book resolves the issue completely. So, I know how to fix it, but not how to prevent it.
If anyone has seen this and has any ideas, please let me know! (I can upload the DGN if anyone thinks they would like to see it.)
Thanks,
Frank Boston
Michigan Dept. of Transportation
Design Survey Support
