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[Proto] Generating Terrain from a Cloud of Points

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  • G Offline
    glro
    last edited by 5 Dec 2014, 09:04

    interesting research

    For organic modeling, it is promising

    but if someone looks for accuracy, there is no solution:

    to be more accurate, you need more points
    the more points ruby has to process, the slower it gets

    i noticed sketchup ruby gets very slow when the amount of data to process increases
    [anchor= goto=:2xytkhdb]http://sketchucation.com/forums/viewtopic.php?f=323&t=59921#p548175[/anchor:2xytkhdb]

    and my experience is that it is getting worse with sketchup updates; SU8 is much faster than SU14

    my guess is that the memory is managed more to make fast render, than answering to ruby questions as "if..., for e in ..."

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    • S Offline
      srx
      last edited by 5 Dec 2014, 09:33

      As we all know this would be VERY USEFUL PLUGIN. Thank you Fredo for all you are doing.

      www.saurus.rs

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      • J Offline
        juju
        last edited by 5 Dec 2014, 09:46

        This reminds me of the points cloud plugin.

        http://www.crai.archi.fr/rld/plugin_details.php?id=292

        Save the Earth, it's the only planet with chocolate.

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        • O Offline
          Openspaces
          last edited by 5 Dec 2014, 10:13

          Thank you in advance for a potential lovely plugin.
          Can't wait 😍

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          • T Offline
            TIG Moderator
            last edited by 5 Dec 2014, 12:40

            A land 'survey' of 'points' will typically use many 'key-points' - taken at clear changes of material, slope, plane etc - and then a general grid of other points - perhaps 5m sq...
            If you link the 'key-points' by clines are they respected in the smoothed mesh's 'edges' ?

            How does it cope with points that are coincident in xy but have differing z values? - e.g. where a retaining-wall has coincident top and bottom points varying only in their z - I know the delauney algorithm chokes !
            The ability to survey in proper 3d [wall-planes etc], rather than the pseudo-3d from a surveyed 'surface' cloud would be a great step forward.

            TIG

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            • F Offline
              fredo6
              last edited by 5 Dec 2014, 14:35

              @tig said:

              A land 'survey' of 'points' will typically use many 'key-points' - taken at clear changes of material, slope, plane etc - and then a general grid of other points - perhaps 5m sq...
              If you link the 'key-points' by clines are they respected in the smoothed mesh's 'edges' ?

              Then, I think it's better to use TopoShaper with the iso-contours. What can however be added is a small plugin to link the points of similar altitudes to form these iso-contours.
              If the points don't have similar altitudes, then we need to use Constrained Delaunay triangulation. Manageable, but again, it requires more calculation and thus takes longer.

              @tig said:

              How does it cope with points that are coincident in xy but have differing z values? - e.g. where a retaining-wall has coincident top and bottom points varying only in their z - I know the delauney algorithm chokes !
              The ability to survey in proper 3d [wall-planes etc], rather than the pseudo-3d from a surveyed 'surface' cloud would be a great step forward.

              Delaunay and many Terrain tools works in XY and interpolate the Z altitude. So walls, cliffs and other quasi vertical structure won't be welcome. Actually, In skecthup, it may be easier to manage first the natural terrain and then introduce the artificial structures by stamping and then push pull or via dedicated tools (plane road paths for instance).

              More generally, I think there are powerful dedicated tools for terrain shaping. So plugins for Sketchup and Sandbox could only be a helper for simple cases.

              Fredo

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              • F Offline
                fredo6
                last edited by 5 Dec 2014, 14:45

                @juju said:

                This reminds me of the points cloud plugin.

                http://www.crai.archi.fr/rld/plugin_details.php?id=292

                Yes, this one is the mother of all triangulation scripts (based on Delaunay), but I think it only generates the first-level triangulation.
                By the way, I think TIG adpated the script to run in recent versions of Sketchup. See http://sketchucation.com/pluginstore?pln=TIG_points_cloud_triangulation

                Fredo

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                • F Offline
                  fredo6
                  last edited by 5 Dec 2014, 14:55

                  @jiminy-billy-bob said:

                  You do everything in pure ruby?

                  Yes. This is pure Ruby. This is fine for small number of points.

                  I am actually quite impressed by the speed of Ruby. But indeed, with more calculations, it gets' slower.

                  The problem I have is that the Interpolation I use is O(M)O(N2), where M is the number of vertices of the triangulation and N is the number of cloud points. So no mystery, it does not scale well. Other interpolations don't give good results

                  The only possibility I see is to convert 2 calculation methods from Ruby to C (each method is 20 lines) hoping that it would speed up a little bit the calculation.

                  But I am too lazy to set up a C development environment, learn the C-Ruby bridging and make it work on PC and Mac!

                  Note that he triangulation is OK in Ruby. I can manage the calculation 10,000 triangles within 25 seconds, so it can stay in Ruby.

                  Fredo

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                  • C Offline
                    cotty
                    last edited by 5 Dec 2014, 16:40

                    πŸŽ‰ πŸ‘

                    my SketchUp gallery

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                    • J Offline
                      jiminy-billy-bob
                      last edited by 5 Dec 2014, 17:37

                      I really recommend doing stuff in C++. Ruby was already pretty fast, but I've seen improvements up to 100 times faster. It's really worth it.

                      25% off Skatter for SketchUcation Premium Members

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                      • F Offline
                        fredo6
                        last edited by 5 Dec 2014, 19:25

                        @jiminy-billy-bob said:

                        I really recommend doing stuff in C++. Ruby was already pretty fast, but I've seen improvements up to 100 times faster. It's really worth it.

                        Sure, that's a possibility to explore. With compilation it might be much faster, because the methods are pure calculation within a loop.

                        But even before I take care of performance, I must first evaluate if the algorithms are relevant for real terrains, which is the reason for my post at this stage.

                        Fredo

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                        • A Offline
                          Anton_S
                          last edited by 5 Dec 2014, 20:09

                          Will be a useful plugin for drawing terrains!

                          Thank you, Fredo!

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                          • K Offline
                            Krisidious
                            last edited by 5 Dec 2014, 20:43

                            would it not be simpler to make point clouds out of polyline topos and then compare the two?

                            By: Kristoff Rand
                            Home DesignerUnique House Plans

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                            • F Offline
                              fredo6
                              last edited by 5 Dec 2014, 21:05

                              @krisidious said:

                              would it not be simpler to make point clouds out of polyline topos and then compare the two?

                              Good idea and actually I did it and obtain similar shapes, but a little rounder with the triangulator.

                              The probleme however is that using iso contour cloud points is already a strong guide to the skeleton of the terrain and therefore does not validate that with scarce points here and there you would obtain a similar skeleton.

                              Toposhaper is based on a linear interpolation whereas Triangulator is based on a directional polynomial interpolation, in order to avoid that each point of the cloud becomes an isolated hill or basin.

                              Anyway, I am not trying to demonstrate that an algorithm can find the good solution because this is anyway wrong mathematically. There are always many solutions.

                              Instead, I am just trying to check if the plugin would be useful to users and landscapers on real cases.

                              Fredo

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                              • F Offline
                                fredo6
                                last edited by 6 Dec 2014, 12:04

                                @krisidious said:

                                here's some files from when I worked at a survey company. some of them are probably point clouds. I'll have to research to find out which. maybe you'll know by looking.

                                I would need something in SKP. I have no Tools to pre-process and I don't even know what are the files.

                                Fred

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                                • S Offline
                                  sdmitch
                                  last edited by 6 Dec 2014, 14:21

                                  @fredo6 said:

                                  @krisidious said:

                                  here's some files from when I worked at a survey company. some of them are probably point clouds. I'll have to research to find out which. maybe you'll know by looking.

                                  I would need something in SKP. I have no Tools to pre-process and I don't even know what are the files.

                                  Fred

                                  Attached is a skp file with both mass points and break lines that you can hopefully use for testing. I have hundreds of such models if you want or need more.


                                  Alaska_NW-DTM 129.skp

                                  Nothing is worthless, it can always be used as a bad example.

                                  http://sdmitch.blogspot.com/

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                                  • F Offline
                                    fredo6
                                    last edited by 6 Dec 2014, 21:31

                                    Sam,

                                    Thanks very much, very useful.

                                    Actually, I have tweaked the algorithm and got the tarrain below. So I think I may finally find heuristics to speed up the interpolation.

                                    sdmitch Alaska.png

                                    There are 1986 cloud points.

                                    The terrain is generated with 3069 triangles. The calculation took 18.5 seconds on my machine.

                                    It seems to be a quite large area and quite flat except a few hill and an overall gentle slope. I had to scale in Z a little bit however to make the relief more apparent.

                                    sdmitch_ Alaska_NW-DTM 129 _ trg.skp

                                    Indeed, if you are more samples, this is welcome

                                    Fredo

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                                    • S Offline
                                      sdmitch
                                      last edited by 7 Dec 2014, 03:05

                                      Fredo,

                                      These models have much more relief. They are bigger with many more points than you would normally use probably. But none of the projects I worked on were small.

                                      Sam


                                      MyDot03DTM.skp


                                      Dem Contours.skp

                                      Nothing is worthless, it can always be used as a bad example.

                                      http://sdmitch.blogspot.com/

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                                      • BoxB Offline
                                        Box
                                        last edited by 7 Dec 2014, 03:47

                                        Fredo if you want, this is a text file of a pair of Scissor handles that I recently managed to import into SU using the above mentioned Points Cloud as a CSV file of over 250,000 points.
                                        It was very slow but worked and I was able to view the scissors in 3D as guide points. I didn't bother with triangulating the faces as it had actually taken several hours to import just the points.
                                        It is without doubt overkill in the terrain context but it is the type of file people will be wanting, if not expecting, to be able to click, copy and 3d print in the very near future. Feel free to ignore it as it was something I found on the web while looking to solve terrain and point cloud imports.


                                        Scissors_handle_points.zip

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                                        • R Offline
                                          roland joseph
                                          last edited by 7 Dec 2014, 11:56

                                          I think it will depend on it's capability for detail. I don't find getting the raw terrain down is very difficult. It is all the detail that has to be built into it...i.e. garden beds, curbs, sidewalks, ditches, medians, grass edge transitions,...etc. For every minute I spend creating the ground, I spend ten on the detail.

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