Featured TUTORIAL LIDAR (Point cloud) to mesh tutorial

Hello,
I have testing LIDAR Data for Road Atlanta, i testing, ReCap, Sequoia, CloudCompare, Meshlab...


But I block once in 3ds max, to achieve a clean track.

PAscal

 

I have been able to get UK point data into 3dsmax.

ASC - LasTools (txt2las) - LAS - Cloud Convert - Merged - points reduced - Made mesh - FBX.

The one problem I am finding is now that I can import KML paths using Mario's track tools or Klaas Nienhuis' KML parser which stay to scale. Terrain I import from point cloud is not which pretty much defeats the object of getting some accuracy to a track!!

Where am I going wrong?

Also once the point cloud becomes mesh, how can I paint grass or dirt onto it (maybe using satellite map as background) ?

 

PseT

I am not quite sure about what you are asking, but I am guessing that you ask about, cleaning away the trees and the rest of the unnessesarry objects.

I only have any real experience with the Danish LAZ pointclouds. In CloudCompare I use the Scalar fields Filter by Value function and only create a landscape mesh, from the surface values.

They seem to have the same values in the Danish files.

What type of pointcloud are you working with?

I ask because one of the difficulties with pointcloud files, is that there are so many different formats, that can contain from few to many kinds of information. It is almost entirely, up to the creators of the files, to decide what they put in there.

3dsmax is way beyond my payscale, so I can be of no help there. I work in Blender.

I wish I could do more, but I am new to this as well.

Happy modding

 

Woodee

I have earlier looked a little into the British data, and I have to admit, that I cannot find head and tail in it.

I know that I have to tell CloudCompare, what to do with the information, but I can for the life of me not find out what. I have never been a number crusher and when I look on one of those files in Notepad+, it's like the letters and numbers begin to swim around the page.

I have no idea for what you should do for your scaling issues. That is also one of the things, I need to work out in Blender for my projects.

3dsmax is still way beyond my payscale ;-)

When you have created your mesh, you need to add a material to it, before you can add a texture.

I would look for add materials and add textures tutorials for 3dsmax, maybe together with the version number, of the software that you use.

My newest attempt will be a mesh, from a full ressolution cloud, where I will add an Ortho photo as texture. You can see how that looks, on a mesh from a reduced cloud in post 9 here:

http://assettocorsamods.net/threads/nisseringen-denmark-lidar-landscape.420/

I will do a retopology on the mesh, that is draping a lower resolution mesh, on top of the high res mesh. I will among other things, use a plugin called RetopoFlow for Blender, that should make it much easier.

When that is done I will add different materials, to the different parts of the mesh. Like dirt, grass, roads, sandtrap and the like. Here I would add basic textures for the materials.

I will attempt to see if I can export 1 mesh, with multiple materials to see how drivable it is.

Otherwise it is time, to split the mesh by material. It is easy in Blender:

Blender 2.76b:
Edit mode / Select object / Hit A until all is selected / Press P / Select By Material

You will need to find a HowTo for 3dsmax.

At this point the continuation is somewhat open.

Happy modding

 

In the UK there is DSM and DTM LiDAR.... one of them is just land, the other includes buildings and things.

I think in Cloud Compare you can crush the height of data so it just takes the ground and nothing else.

 

I know how to map material in max, it's just that the LiDAR I import which is not to scale, it would be hard to match up with a google map that covers the data.

I'll have a look for a retopo plugin or method in max as this may be more useful than conforming low dense mesh to the (somewhat) dense mesh imported. Trying to import the most hi-res 50cm/1m LiDAR makes my computer hang (i7 6700 16 gb RAM), I have to tone it down a little before importing it in a manageable state.

I use LAS Tools (txt2las) to convert from ASC (which is what the UK data comes as) to a LAS then I can use Cloud Compare to make a mesh from it (OBJ/FBX etc...)

Once I have a few things figured out in my workflow and find some decent way to overcome these problems with scale, I will post it up.

Glad these places exist to help each other modding

 

Woodee, it sounds like you're using the ASCII format grid data that was generated *from* LiDAR data?

That is what I've used and posted about it in another thread on here.

If that is the data you're using (which it sounds like it is), then the scaling is an easy fix because the space between each vert (xy plane, not actual edge length as they slope) is the distance marked in the meta-data at the head of the ascii file. Ie, 50m, 5m, 1m, 50cm, whatever.
The Z (height) values are in absolute metres, so the bottom left point on the grid should have a Z height of the first value in the file after the meta data.



PseT, that data looks pretty nice.

But there is no 'button' to make any task easy. This is just 3D blueprints, so you still have to do lots of work to get a nice track.

For example, defining chunks as trees, the track outline, removing features etc, are all done manually in real life. It's one of the main reasons LiDAR data is so expensive... all the manual work tidying and filtering and defining objects.
I've spent weeks with another chap just outlining the road edges on 20km of road LiDAR data before... so yes the road was accurate for sure, but it didn't just happen, it also took huge amounts of work to get the data out of points and into a grid perfectly matched to them


Cheers

Dave

 

erm.....

 

Hey Woodee,

The scaling issue you have is easily fixed.

If your using a 1m DTM or DSM for instance, then the top-down grid sizing is 1m. So as long as the imported grid has 1m x 1m squares in the top-down view, then it's to scale.

Or 50cm for a 50cm DTM/DSM, and so on for the other sizes.


And to clarify on those data-sets, they're not LiDAR data. They are DSM/DTM grids made from LiDAR scan data. So they're accurate but they're not point cloud data. You can't load them in point cloud software.


One other thing to note is that the grids are not covering the entire area on OS grids, since the very last row (top of grid), or very last column (right of grid) are left with a gap the size of the grid density (1m, 50cm or whatever the resolution is), since the last row or column of data needs to fill the gap up to the next strip of height data points.
Simply put, don't load several tiles and place them right up next to each other because that is incorrect, the need offsetting by the grid size value.

Dave

 

I let the cloud software stuff work that all out.

I'll have to try just doing it with one tile and see what happens. Unluckily a track spans the borders.

 

Yeah the software you're using should figure it out.

If your software keeps the meshes split by grid import, but sorts the seams and alignment, then just export one at a time to your 3D app so it's smaller meshes as possible.

If it's joining them then the meshes will get huge and the 3D app unhappy I think haha

But it might still be ok if you can get the import to work, albeit slowly and sluggishly. You can always split the mesh up in your 3D app later into managable chunks



The main thing is to be aware of what the data set really looks like, so you can check the software is dealing with it right and doing the seams and so on.
I did lots of testing on the OS open data 50m DSM models which are the same data type, but much faster for processing/testing with to check things work right. Also any discontinuity at edges is really easily visible with such a large grid size too!

Dave

 

SO far I've not found a happy (not slow) compromise and I'm running a i7 6700 with 16 gigs of DD4!

When I get some of my brain matter back I will test 1 square (25cm/50cm/1m). I bet I still need to lengthen the space between points to make the mesh easier to handle, but we'll see.

 

i7 4700k here with 16gb of ram too, and a dedicated fast SSD for swap file etc etc.

Those meshes kill my computer in most 3D apps too.

The 25cm ones are like 16 mill quads, or 32 mill triangles!

50cm are 4 mill quad, 8 mill tris.

1m are 1 mill quad, 2 mill tries (they start getting managable as whole chunks now!)



For the finer detailed ones you just have to chop them up really and then manage them in layers or whatever else.


But to lengthen the distance between points will make the grid out of scale. If the size is 25cm for instance, then the grid is 25cm, so 4000 x 4000 squares = 1km x 1km in size.

50cm = 2000 x 2000 squares = 1k x 1km

1m = 1000 x 1000 squares = 1km x 1km

Etc.


The only way you could increase the distance between points is to make the grid out of scale.

 

I don't think any of the tracks I am currently looking at have 25 cm

I will have to see what I can find and grab a small square of 25cm to see what it is like Hoping my hefty rig can cope hahaha

 

I suppose a way to keep it to scale and keep res would be.... cutting the smallest possible chunk around the track and importing that. Experiments to do

 

The 25cm data isn't much better than 50cm really in my view, since you just start seeing more of the noise than more sharp details it seems.

50cm is good over 1m mainly because at 50cm the noise/error of the data is just starting to show.

For most stuff 1m is pretty good though.

I've imported 50cm (the best data) for a project I'm working on, and then have the 1m for everything beyond the main track/driving area since for all intents and purposes it's just as good as a reference.


On the other thread on here I've added a load of info/pics of which tracks are covered by the UK DSM/DTM grid data so far... so if you're looking at more that are not on there it'd be cool to add them for others so they know for future reference maybe

Cheers

Dave

 

I am so dumb...

it was the "Creating a reduced resolution Mesh" bit in this thread... did that mess with my scale of the mesh imported? Not sure STL is the only format to save to which is compatible with 3dsmax.

 

I've no idea what your software does unfortunately.

I have a feeling it may just trim rows/columns to reduce the resolution then. That should be ok if that is what it's doing, but it'll be lossy of course. Better to just download the next grid size up really. Ie, get 1m instead of 50cm, if you want to reduce the resolution any way.


This is where working on the Open Data DSM/DTM which are 50m grids is better as it's super fast and easy to check/cut up and test things with so you know what's happening

I can happily send some of the 50m grids to you for testing if you wanted?

Dave

 

I have used to software mentioned in this thread for my workflow experiments.

It's ok, I'll grab data from local places so I can check accuracy.