Best practices for pasting

[cadtag]

I've got an old surface, generated from GIS, of some pretty hilly/steep terrain. Eventually, a small and critical portion of that area is located with finer resolution lidar data, and delivered as a point file.

I've edited the resulting surface2 to get rid off long tin lines around the perimeter that were skewing the results, and pasted it into my surface1. Is there a better way? I am still seeing small jogs in the contour lines (new data is not a perfect match with the old, so the contours in the resultant surface have small jogs at the intersection. Not enough to make a huge difference, but enough to look odd - like someone took a hoe and cut a linear swale around the intersection.

[trevor.hatch]

You can always remove some of the points that are close together from the point groups included in the surface. Also you can turn triangles on in surface style and swap edges until it looks right, or at least better. You'll never get a perfect match, but you can play with it to get it to look better.

[cadtag]

Only two data source, no real point groups. 280k plus pts in the update lidar pnt file, and 246 Mb of data in the XML file that GIS created. I was/am really hoping for some expedient way to 'fair' the pasted surface into the target surface.

I've done a lot of triangle whacking to get it better, slow going even on a fast machine, but the final contours still have that jag.

[Opie]

Just throwing this out there.

Could you generate a couple of feature lines? The first would be around the perimeter of the LIDAR data and sent to the LIDAR surface for elevations. The second would be an appropriately spaced area for a buffer between the LIDAR and the old data and sent to the old data for elevations. Now, create a third surface and use these two feature lines as breaklines. Paste this third surface into your final surface.

[cadtag]

Hi Opie,

That sounds like it might get there --will play around tonite - probably try go inside the LIDAR a few feet with an offset shrinkwrap, and outside 10 ft.

[Opie]

If you remember, would you mind let me know how it works out? Thanks.

[cadtag]

Good suggestion Opie!

slow process, but good results. if the area wasn't 14 miles long it would go a lot quicker....

Basically I use shrinkwrap to get a pline around the update surface, flattened it, then offset that 10' either way. I removed the ends of the boxes, to end up with four plines running the length of the GIS surface. then, converted the outside two plines to features lines, assiging elevations from GIS, and did the same thing with the two inside plines, assigning elevations from update surface. Connect the two west feature lines with 3d pplines. and run shrinkwrap again (so i'll have a tight border). Create a West surface using those two featurelines and the connecting 3dpolys as breaklines, and the shrinkwrap as the border. and paste that into the composite lidar/gis surface.

here's a close up the original problem
before.PNG

and here's an interim showing the fix in progress. the two yellow lines are the borders of the 'fairing' surface.

interim.png

[Opie]

Looks good. Thanks for writing up the process with pictures.