Subscribe to this thread
Home - General / All posts - M9 Triangulation to Contours - how?
Jono3 post(s)
#08-Mar-18 20:44

M9 Triangulation

Okay, know my way around M8 and contouring has always been simple. But, I have been given a 7 million point csv that I would like to generate contours for, M8 won't do it, it grinds to a halt. The original XYZ file that the CSV originates fails at 50% import in M8.

I have got the data into M9 added fields and geom and can create a beautiful trainagulation....BUT what is its purpose? how do I get contours from that trainagulation. I agree its quick but I have burnt s much time expecting to find the contouring option on a trinagulation. What am I missing, please help!


8,401 post(s)
#09-Mar-18 09:28

Manifold 9, similarly to Manifold 8, composes contours using raster data as an input, not vector data.

Try importing XYZ into Manifold 9 and building contours on the result.

Perhaps it might make sense for us to add means to build contours directly from vector data as well. In your case this is suboptimal because the original data, as you say, is XYZ, but for cases where the original data is vector, it would be good to not have to go through a raster (not even a temp one).

489 post(s)
#09-Mar-18 16:45

Perhaps it might make sense for us to add means to build contours directly from vector data

Adam, by "vector data" do you mean point data say from LiDAR? I'm involved in a project where a contractor has flown and provided LiDAR data in the form of ortho photos and point elevation data. There is also a .gdb folder. Another consultant is doing the GIS for this project using Arc and he's successfully pumping out contour maps. I have the data from the LiDAR contractor and for interest sake would like to be able to generate similar products. Nowhere in the LiDAR data we received do I see DEM raster images. There is a .GDB folder but no data are imported to M9 when I try to do File > Import > .gdb In tests with sample .gdb folders I found on the web I can successfully import data into M9 from .gdb folders confirming I am following the right steps to work with .gdb folders.

In another thread someone suggested the software to generate DEM from point elevation data is very expensive, in the tens of $$. If M9 can generate contours and other products from point elevation data, x y z, that would be great. Apologies if I don't have the terminology correct.


8,401 post(s)
#10-Mar-18 06:13

Yes, I meant that it might make sense for us to add means to build contours directly from points with heights, like LIDAR. Maybe also from lines with heights (re-contouring).

560 post(s)
#09-Mar-18 22:31

Don't know how this bears on the issue, but here is some information about the point clouds I received in LiDAR (.las) format. The attached image shows about 1 square mile of ground reflection points (13 million plus points). The Z value, say 39266, represents a point 392.66 meters in elevation. I happened to receive .dem data in addition to the .las data. Had I not received the DEMs, I would be looking for a way to connect the dots at equal elevations to create contour lines separated by 1 meter in elevation. I suppose some people could benefit from seeing these points as a surface.

Bandera Ground Point Cloud.jpg

Jono3 post(s)
#10-Mar-18 03:48

Thanks Adam, yes, to me it would make sense to be able to contour the triangulation (what else is it for?), Can you help me out, workflow in M8 would have been:

1. Import points file as CSV

2. copy points, paste as surface.

3. create contours from surface.

In M9, what is the process?

1. import points file as CSV

2. Add geom field etc and populate point with z.

3. Whats next?? how do I get to contours, can I make a surface?

Appreciate some guidance here.




6,292 post(s)
#10-Mar-18 06:11

Straight Forward wound be to have a tin, a 3D-vector plane and to have all sorts of functions like add, substract and contours to Work with them.


8,401 post(s)
#10-Mar-18 06:15

You said you have XYZ which 8 could not import. Try importing it into 9. This will create an image. Run one of the Contour transforms on that image.


8,578 post(s)
#10-Mar-18 06:43

I think that by XYZ the OP (Jono) has always meant CSV with X, Y, Z columns.

That is, LiDAR vector data.

I could be wrong.


8,401 post(s)
#10-Mar-18 07:02

If there are only vector points and no raster, and the amount of vector data is too big for 8, then (a) wait until we add converting vector to raster to 9 (this is coming, similarly to contours we want to improve the feature we had in 8: make it work for huge amounts of data, make it faster, etc), and (b) in the meantime, convert vector to raster using a third-party tool (GDAL?).

Jono3 post(s)
#10-Mar-18 10:31

I think that by XYZ the OP (Jono) has always meant CSV with X, Y, Z columns.

I did mean a xyz file, and Manifold failed to import, got to 50% and stopped (it could be the file)? Manifold 9 failed completely in the import, would not even start to process, and then crashes.

Because the xyz failed I converted to a csv, with an xyz. For some reason the newest version of 8 would not turn anything into a surface, stalled each time, even after I had chopped into smaller files. So I suspect there is something at fault in the M8 version or at least in my install. This used to be such a reliable feature.

OK so that's what I needed to know. I can't use M9 to create contours unless I already have the surface created (which would be easy in M8 if it wasn't crashing/ stalling...let it run for 12 hrs only 1%). Would be a great thing to add to help - go to M8 if you want contours from data other than a raster.

Look forward to seeing Manifold 9 become the trusted software I have known of the past, its showing promise.

Can anyone explain what the triangulation is actually for in M9? Is it just experimental?


8,401 post(s)
#10-Mar-18 13:21

Manifold 9 failed completely in the import, would not even start to process, and then crashes.

Wow. Sorry to hear that. Can we have the file? If it is not too much of a hassle, please send a bug report to tech support and offer to upload the file (I am guessing it is big, so ask where to upload it and they will provide you with FTP space).

Same for the CSV which M8 fails to turn into a surface - please report that as a bug to tech support. Or just upload the file somewhere and post a link here. I assumed that M8 fails to create a surface because there is too much data (for M8), but since you say that the process fails even if you chop the file into smaller portions, that might be something else. If you post the file, we'll be able to check what's going on.

Triangulation is useful as an intermediate step for a great deal of things: computing volumes, distributing numeric weights, etc. You can also use triangulation + script to do more complex things (like contours) if you don't want to wait until we have that built-in.

For what it is worth, turning a set of points into a surface is not too far down in our queue for 9.

Manifold User Community Use Agreement Copyright (C) 2007-2017 Manifold Software Limited. All rights reserved.