Creating Geopak TIN files from LAS files

I have several hundred .las files that need to be converted to geopak ,tin files. Is there any way to create a batch that can do this?

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  • There is not a batch routine for converting LAS to TIN. You can multiple select LAS file to import into Terrain Models in SS3 or SS4 but then you would have to export them one by one to a TIN.


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  • Hi Josh,

    It could simply be an issue of too much data to process for a single TIN...
    Possibly, you might have to go the route of creating a ScalableTerrain Model using Descartes.

    Regarding adding the breaklines.... Something I've not tried - so I'm guessing here.
    It would depend on what tools are available for editing that multi-resolution terrian.
    My first thought would be...
    Attach the SHP as a reference file and see if you can copy the graphical data from the SHP into the DGN.
    If yes, maybe there are tools to insert the breaklines into the MR Terrain in a similar manner to what you'd have previously done using the GEOPAK SS2 DTM tools.

    I don't have Descrates loaded at the moment (and its home time). If you dont get an answer, I'll load it tomorrow morning and take a look.

    HTHs,
  • Thanks Michael,

    I am able to copy the SHP breaklines into a DGN, so that's a start. I haven't looked into how to add them to the terrain yet.

    I'm not sure what to do with a STM even if I am able to create one. Will that be usable in GEOPAK, or is that just a Decartes format? Will that get me closer to a City-wide GEOPAK TIN file, or should I just abandon that idea altogether and live with the fact that I will have to work with much smaller-area tins from now on given the sheer number of LiDAR points? It seems like a step backwards in a way.

    Thanks again,
    Josh
  • Hi Josh,

    The further I look, the messier it gets.
    Firstly, let me say that it has been mentioned to the Bentley folks that a STM, that cannot be viewed by all Bentley applications, is less than useful. Aparently that suggestion fell on deaf ears.

    Moving right along.
    I installed Descartes and took a look.
    You can export a STM to one of the new SS3/SS4 MicroStation "Terrain" elements. I had hoped that I would be able to set the level of resolution when exporting - but there are no options for that. What does control the resolution of the exported terrain element (according to the HELP) is a config variable (STM_DOWNSAMPLING_PREFSIZE) which is the size in MB of the terrain element that will be created.
    It would have been nice to be able to select one of the internal resolutions stored within the STM and "test" the size of the resulting terrain element before the export... but that isn't there.

    So, potentially, you could create an STM and then export it to a terrain element, then save that as a TIN.

    The other option (assuming you are still looking for the entire city TIN) is to install GEOPAK SS2 and go to the Data Aquisition tools.
    In there, you can build a DTM from the attached LiDAR point cloud. The nice thing is that before you try and build the DTM, you can sample how many points will be extracted. The dialog allows you to set the filtering and then test it.
    If you can set the filtering to an acceptable value and still build a reasonable size surface, you're good to go.
    Use a "fence" to create the DTM for exactly the area of interest.
    Once a DA DTM is created, you can export that to a TIN.
    If the filtering needs to be set to high, you may need to find a solution other than a single TIN file.

    Whats an acceptable filtering value?
    I would typically start with the value that is the accuracy of the collected data. It was typical that aerial LiDAR had an accuracy of +/- 6 inches. So I would use that 6 inches as the filter value - at least to start with.

    Yell if all I've done is confused the matter. I can call and discuss.

    HTHs
  • Michael,

    Thanks for looking into this as much as you have. I have found a reasonable workflow. I have attached all of my LAS files to a single dgn file as MicroStation Point Clouds. This doesn't give me any issues. I'll just have to work with smaller areas when creating a Terrain (and ultimately a TIN file). This still allows me to fence around an area of interest, picking from the entire city. I feared that I would have to attach the LAS files in question for each and every project we do. This could be problematic if a project spans multiple LAS tile areas. Figuring out which LAS tiles to use each time would be a pain, but the method I described still allows me to look at the entire City and then narrow it down with a fence, not worrying about whether or not I am spanning LAS tiles.

    Thanks,
    Josh
  • Good Josh,

    glad you found a solution.
    MicroStation does an awesome job of dealing with PointCloud datasets. Very fast and allows huge datasets.
    If that does what you need - you're set.

    Cheers,
    Michael
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