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Contour Generation cutting off on high elevations

I’ve never had a problem in previous versions of pix. Starting 2 weeks ago every job I process now cuts off contours in the higher points of each separate job. It has correct elevation data when I view the point cloud and also when I pan over the orthomosaic but when i let the program generate contours then its incorrect. Please help me or show me how to export the points and I can generate my own contours in the Agtek software I use for earthwork calculations.

This sounds similar to this other post: DTM removing hills peaks

Do you have the same issue? Can you post screenshots of your contour lines processing options? Maybe some examples of what the badly generated contour lines look like? Some quality report? More information would definitely help to investigate the issue. 

Here is how you can export the point cloud: How to export the Point Cloud

Dose this issue get any solution?
I havd same problem.

It seems like it has got better but, i’ve had to go back and check the point cloud classification (As colors) and reassign certain areas.  Then you will have to process again.  This helps but with a lot of editing.

Thanks, John.
Actually, I’ve done the procedure you suggested. I re-group the “Building & Human Make Object” to “Ground”. The situation above mentioned improved but the z-value error still too large to accept.

I thought the options of Contour lines “Resolution” & “Minimum Line Size” should be the key point. But I didn’t know how to adjust those options.

Could someone help out?

Until pix responds, try changing them to 60/30. Also run your vertical in 1’ intervals

I think I used to run 240/120 when I was having major issues. Let me know how the 60/30 works too Lung

In my project, the terrain includes riverbank, road, and riverbed which most areas were dry. The height difference between riverbed and riverbank is near 5-meters.The DTM result of Pix4Dmapper satisfied to me. In the interface of raycloud, I could see my survey points were very close to the point cloud in many areas of the terrain.

As the workflow of my company, we just need the contour lines of DTM for our follow-up procedures. We don’t want the DTM-tiff images.

But the problem is, the contour lines of DTM which generated by Step 3/Additional Outputs/Contour Lines was confused me. 

For testing, I set the interval of contour lines=0.1m, Resolution=1000cm, Minimum Line Size=20. The result of the experiment, the contour lines of height was lower about 1.8m than my survey point on the top of the riverbank. In most of the riverbed and the road, the difference was acceptable.

It’s so confused me. Could someone tell me where I’m wrong?

 

I guess…I knew why “Contour Generation cutting off on high elevations”.

As the screenshot picture, the black line generated by the function of Pix4D DTM’s contour line, the green line is contour lines generate by Virtual Surveyor. There are 2 yellow cross marked by the blue circle. The below one is my field survey point that its height is EL+181.23. The above blue circle is the highest contour line(=180.20) generated by Pix4D.

Why Pix4D didn’t generate the contour lines between EL+180.20~181.23. Remember I set the interval=0.1m, Resolution=1000cm, and Minimum Line Size=20 vertex?

That should be the cause why Pix4D cut off on high elevations. Because, between EL+180.20~181.23, the disappeared contour lines are too short to generate.

You can see the 2 blue circle. There are two contour lines(green color). But they are too short which can sample by the “Resolution=1000cm”, or the vertex of those contour lines are less than 20-vertex. That’s why those contour lines didn’t generate from the DTM.

Am I right?

Yes, I think you are right. I would try to decrease the resolution, it’s rather large at the moment with 1000cm (10m). The default options are at 100cm (1m).

If you want to get a feeling for the influence of the resolution and minimum line size parameters, I would modify these parameters in the processing options and then only regenerate the contour lines with Process > Generate Contour Lines (DTM). This will enable you to quickly generate several versions of the contour lines for the same DTM, so that you can compare them without having to reprocess the entirety of step 3 each time. 

As you discussed higher up in the post, the classification of points in the point cloud needs to be verified before generating the DTM. If this is not correct, the contour lines will not be either. You can always reassign points with the point cloud editing tool