3D Analyst Survey and Tin

Question

I'm fairly new to 3D Analyst and Arc TINs. I understand the concepts of a TIN and have worked with them extensively in the CAD environment.  What I am trying to accomplish is incorporating point shots created by a surveyor across a stream (essentially a stream cross-section) into a TIN created f/ LIDAR data.  I need the TIN to actually recalculate the triangles instead of just dropping in a new point b/c I am exporting my data to HEC-GeoRAS for stream analysis.  I have used the add features to a TIN tool and it didn't produce desirable results.  Pretty much what I need is for the data in the TIN along the cross section line to be invalid and use the surveyed point shots.  Sorry if that wasn't a great description. Any help would be greatly appreciated!

JakubSisak · Answer

clayton62:

I did end up using breaklines to represent the surface at the cross-section locations. I had to use hard breaks b/c the softs still weren't triangulating correctly.

One thing I am struggling with now is how to combine to TINs in some way.  I have streams that tile across several grid sections (each containing a separate TIN).  I need some way to read a cross-section across those separate TINs and can't do it if a XS spans over two different TINs.  At least I'm not sure how. 🙂

Thank you for your help.

-emiller

What i do is to design a perimeter around the area i want to update. This needs to be a 3D line feature as i will use it later in the process. Then remove all TIN nodes within the perimeter and add your new points. Lastly add the perimeter 3D break line.

ClaytonCrawford · Answer

How large are the tins? If the sum total of nodes is a few million nodes or less than make one large tin. If you have the source data use it to build the tin. If all you have are the tins you can run the GP tools TinNode and TinLine to decompose them back into features and then use them to make the unified tin.

If you have more data than can/should be used to build one tin consider using the terrain dataset.

Clayton

EmilyMiller · Answer

clayton62:

I did end up using breaklines to represent the surface at the cross-section locations. I had to use hard breaks b/c the softs still weren't triangulating correctly.

One thing I am struggling with now is how to combine to TINs in some way.  I have streams that tile across several grid sections (each containing a separate TIN).  I need some way to read a cross-section across those separate TINs and can't do it if a XS spans over two different TINs.  At least I'm not sure how. 🙂

Thank you for your help.

-emiller