Hello Marballe,
Your understanding is correct.
1) Trying to edit a TIN file that large would be very slow and likely to crash (run out of available memory blocks large enough to load/store the data)
2) The TINs/DATs do need to be overlapped to merge them.
I’d suggest you use an alternative method to create you TIN and contours.
1) Create a single PointCloud in MicroStation, using the PointCloud tools, by importing the 16 LAS files.
2) Use the GEOPAK Data Acquisition (DA) tools to build a single Surface across the area you are interested in.
a. If you do not need the entire area, you have the option to place a fence around the area of interest and extract the LiDAR data only within that fence area.
b. You have the ability to filter LiDAR points out of your Surface based on a Z tolerance when importing the PointCloud data.
i. A “rule of thumb” tolerance value would be your LiDAR expected accuracy value. This might be an initial option and, depending on the result, you might then halve the Z tolerance value and try again... This should significantly reduce the size of your Surface while still providing a good result relative to the accuracy of the LiDAR data.
c. You have the option to extract points from the LiDAR data based on their classification. If your LiDAR data is classified, you can remove the classifications that are not applicable by disabling their classification from the view before importing the points to the Surface.
3) Once your Surface is created, export the Surface from Data Acquisition to a GEOPAK TIN. It’s a right click option. Select the Surface name, right click, export.
4) If you wish to exclude areas from the TIN or DA Surface, you can draw shapes into MicroStation across the areas you wish to omit and add those shapes as “drape voids” to your TIN or Surface.
Hopefully, this will provide the result you are looking for.
Michael Gilham
Global Solution Lead - Civil
HATCH
Direct: 61 7 3166 6142
www.hatch.com.au