Ground Contours and Objects such as trees

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi, i want to generate contours but on a ground level. how can i get the objects such as buildings and trees out of the way? Is there a way in mapper or should it be done in Autocad or Microstation? and if so, how to you do it?

2

You can create a DTM, which is void of tress, objects etc.
Click Process > Run Terrain/Object Point Cloud Classification (beta), then in RayCloud, EDIT the point cloud to move any points left-over from the trees, buildings, etc to the DELETED point group. You only want ground points in the TERRAIN Point Group. Un-check all Point Groups besides TERRAIN to confirm.
Click Process> Generate DTM (beta).
You will have a true DTM (Terrain Model, not just a Surface Model)
Now when you generate contours, they will look as you are expecting them to.

1 Like
3

Pix4d also has a How-To related to your question:
https://support.pix4d.com/hc/en-us/articles/203722389-How-to-Generate-Contour-Lines-Based-on-the-DTM

4

I made a comment in an email from a Pix4d salesman, he forwarded it and got what I considered to be a less than satisfactory response from support. I feel like they need to hire a few more industry consultants to go along with all the software engineers.

My comment:
The export options could be a little more friendly to surveyors/civil engineers by including a TIN option (https://en.wikipedia.org/wiki/Triangulated_irregular_network) in either DXF or DWG
Building the DTM/TIN on the ground (without classed objects, trees etc) should be default, nobody wants contours over buildings and trees, ever. (I had to Google for some work around that seemed hacky)

Relevant part of response:
As far as the point cloud classification is concerned, it is true that it is not selected by default. However, you can create your own template and save the point cloud classification to run for every project that this template is selected.
For step by step instructions, please check: https://support.pix4d.com/hc/en-us/articles/205507149
However, note that it is not possible to create the contour lines based on the DTM automatically, as you will first need to assign all the object points to the deleted project group.
For step by step instructions on how to generate the contour lines based on the DTM, please check: https://support.pix4d.com/hc/en-us/articles/203722389

5

Hello John,

That part of the answer was complementary to the main part related to the TIN files question:

“Regarding the TIN output, it is true that Pix4Dmapper does not generate the TIN. Why would it be useful for you? You can generate the TIN from the las in ArcGIS.
For step by step instructions, please check: https://support.pix4d.com/hc/en-us/articles/202559569”

Maybe the answer was not so descriptive so we can try again in more detail here:

At the moment we do not generate TIN files for the DTM or TIN files that comes together with the contour lines.

It is a good suggestion (as the other ones you pointed in your email) and we have passed it to the product development team so they can consider it for future releases (we receive many suggestions which makes as very happy and proud, but we cannot place them all or place them all at the same time, step by step we are adding many functionalities in the software).

As far as we understand, the mentioned suggestions in this post are (let us know if you wanted to mean something else):

  • Generate a TIN file of the DTM.
  • Add the DTM generation as an option in the processing options so it can be generated within the step 2.

At the moment there is a workaround, which is not very automatic (it will require several steps and time consumption but still it is possible to do it):

Regarding the DTM generation, it is possible to modify the processing template so always the point cloud classification is performed, run steps 1 and 2, and then via the process menu bar, generate the DTM.

Since the TIN files are not generated with the DTM or contour lines, it is possible to move the points of the objects group into the deleted group, change the processing options to generate a low resolution 3D textured mesh in .fbx or dxf format. and then via the process menu bar, generate 3D textured Mesh.

Let us know if we can assist further,

 

 

 

 

6

Hello John,

 

I am a land surveyor trying (like John Slaughter) to utilize this in a real world application as we (surveyors and civil engineers) know it. This means the main tool we would need is to create a tin surface to go directly into Civil 3d and Microstation. We don’t feel it should be necessary to run the data through 3 different software’s and multiple plugins to accomplish that. Most surveyors an civil engineers do not have or need GIS software. This is the main limitation to Pix4d that I have found. I do think it would benifit Pix4d if they had more industry consultants so the outputs were more usable to the engineering industry.

 

Thanks, and you guys do a great job.

 

Just my 2 cents.

7

Hi,

Does anyone know if they have fixed this or will be in a future release?

I have the latest version of Pix4D and it still doesn’t work without work-a-rounds.

 

Thanks,

Steve

8

Hello All,

Any updates on this thread?  I am in the same situation, as a land surveyor, regarding TIN export from DTM directly to AutoCAD.  I kindly ask that the Pix4D team look into this issue as more and more surveyors/engineers will use your software!!!

Thanks,

L. Joy

9

I’m with John and Blaine. I would like to see TIN output as well. Just a suggestion.

10

Hello all,

Unfortunately, the development of this feature is not planned for the near future. As such, we cannot give an estimate for when this would be available. The workaround of using QGIS or GlobalMapper remains valid (as far as we can tell) to convert the GEOTIFF raster generated by Pix4D to TIN format. 

Please not that regarding the DTM comments made above in this thread, there is now a new method in Pix4D 3.1 to generate a DTM without classifying the point cloud. 

Best regards,

11

Hi Marc,

About generating the DTM on a ground level in pix4d and then exporting it as countorn lines stills an issue for me. I am not having troubles classifying the point clouds. In the tutorials it talks about that DTM automatically generates itself from the labels Ground  and Road surfaces, but the results still contemplates the trees and buildings, so does the countorn lines. Of course is better than the DSM, but still.

I am using another software to create the countorn lines after processing the point clouds I generated in pix4d, but I prefer to get the results from Pix4d. Maybe is something I’m missing out.

12

Hi Victor, 

Please create a new post for your issue, so that we can investigate in more detail. This post is already quite crowded with information. Please copy the information you have posted here and add information about the version of the software you are using as well as adding a quality report and log file if possible. Thanks!