User Forum of Software BASEMENT

david

User

Registered: 2015-07-24

Posts: 2

Trouble with running TRIANGLE via BASEmesh

Hello,

I'm working through the first tutorial (Mesh Generation based on Pointwise Elevation Data) in QGIS 2.8.2 and have hit a road block.  The steps for "Creation of the Elevation Model as TIN", I have tried two different ways:

1. using the boundary layer and elevation points that I've created following the previous steps and

2. using the boundary layer, elevation points and breaklines that are given in the additional files in the .zip folder.

In the Elevation meshing steps I enter all the information as outlined in the tutorial, but the error "meshing failed" comes up.  The status message reads as follows:

prefix of triangle output-files: BASEmesh_tutorial1
plugin directory: C:/Users/crwr-drr883/.qgis2/python/plugins/BASEmesh

'triangle' successfully initialized...

PROCESSING INPUT DATA...
field with elevation data: X

> no breaklines specified <

TRIANGLE INPUT file BASEmesh_tutorial1_Elevation.poly successfully written

> EXECUTION OF TRIANGLE... <

Triangle: MESHING FAILED.

Any information as to why the triangle meshing failed would be greatly appreciated as I am unsure of how to troubleshoot this program.

Thanks,

David

Sam

Developer

From: VAW - ETH Zurich

Registered: 2014-09-04

Posts: 46

Website

Re: Trouble with running TRIANGLE via BASEmesh

hi David,
commenting your troubles from the distance: this sounds like a problem that is linked to TRIANGLE and OS-SYSTEM issues ...
1. what operating system are you running?
2. check the permissions of the directory where the TRIANGLE executable is stored.
3. check if your TRIANGLE is executable via command line.
cheers

qtheiler

User

Registered: 2015-07-30

Posts: 60

Re: Trouble with running TRIANGLE via BASEmesh

Hi,

I have also the same error message qhen I don the quality mesh and then it said out of memory in the error message (it hase used 4 GB of my 32 GB (8 process). How can I solve this using all the memory?

Best regards,

Quentin

Sam

Developer

From: VAW - ETH Zurich

Registered: 2014-09-04

Posts: 46

Website

Re: Trouble with running TRIANGLE via BASEmesh

from your descriptions I'd guess that TRIANGLE did not find a valuable mesh. When creating the mesh, more and more triangles are added until some conditions are fulfilled, i.e. if the algorithm does not converge it fills up your memory... without successfully creating the mesh. also you get into troubles if the distance between two mesh vertices is not much larger than the arithmetic precision of your machine.
please consider these remarks:
1. define your mesh around the origin (0/0) of the coordinate system, achieving more floating-point precision with TRIANGLE
2. the option tag -q has assigned a too high angle (usually around 34° is the upper limit)
3. two points have almost the same coordinates (but not exactly). be sure to use the snapping option of QGIS!
4. points that are close to breaklines and/or boundary polygons. either you include these points to the line/polygon, or make sure they have a certain distance from the line/polygon
5. breaklines that intersect at extreme angles
for further information how TRIANGLE works, see developers website
cheers

david

User

Registered: 2015-07-24

Posts: 2

Re: Trouble with running TRIANGLE via BASEmesh

Hi Sam,

Thanks for your response.  It was due to TRIANGLE requiring administrative privileges to run on my machine.  I've now run through the tutorial and everything worked well.

Thanks again.
David