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.
Sent: Saturday, 10 May 2014 8:05 AM
To: MicroStation@communities.bentley.com
Subject: [MicroStation Forum] LiDAR Data & GEOPAK
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Background I am using MicroStation V8i w/ GEOPAK SS2. I obtained a ton of LiDAR data that covers about a 12-mile-by-2-mile area. The LiDAR data exclude all the surface waters (such as ponds, wetlands, rivers, and creeks) that are wider than 50 feet. The data comes in as 16 LAS files and 16 ASCII text files (X,Y,Z). My goal is to generate contours using the LiDAR data.
What I Tried & Problems... I am able to use the DTM Tools to extract the 16 XYZ into a single DAT file, build the triangles (as a TIN file), and then generate the contours. The DAT file is about 750 MB and the TIN file is about 1.2 GB. But this also generates triangles in locations without LiDAR data and create some really obscure contours.
I tried the Dissolve Side option with 50 feet when building the TIN; but as you probably know, the dissolve only works on the external sides, not internal.
I tried to remove those triangles manually using the DTM edit tool; but the TIN file is so big that it crashes MicroStation. And let's be honest, I really don't want to manually fix a 12-mile-by-2-mile area.
Am I missing something? Any suggestions? Thanks in advance!!
p.s. The reason I combine all the XYZ into a single DAT and a single TIN was that in order to merge two TIN files, they have to be overlapped (at least that is based on my understanding; so, correct me if I am wrong). The 16 files are not overlapped, but next to each other...
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