I’m somewhat experienced when it comes to using Pix4d Mapper, but recently have become frustrated with the lack of Geoid and Vertical Datum support. I also have what I assume is an edge case use, where I need to export ~50 surfaces on every project (mapper requires each surface to be exported separately if you want to retain each file without combining them all into one file)
All of this has led me to evaluate Pix4d Matic and Survey. While I am so far impressed with the speed improvements, there doesn’t seem to be any way to edit the point cloud before processing the DSM. In Mapper you assign what you don’t want on the disabled layer, then process the DSM. According to the Mapper support article: https://support.pix4d.com/hc/en-us/articles/115001671066-How-to-improve-the-Outputs-of-Pix4Dmapper#label6
"How to improve the DSM
The DSM receives as input the point cloud. If the point cloud is noisy, the DSM may also be noisy. Make sure that the results of step 1 and the point cloud are optimal before generating the DSM. However, if the DSM is still noisy, there are some actions to be taken:"
Anyone else experiencing the same circumstances? What have you found as a work around? Or am I missing something completely in front of my face? Any help is appreciated.
Hi DroneLink,
The workflow using PIX4Dmatic and PIX4Dsurvey is a bit different than PIX4Dmapper. The most notable difference is that Mapper derives a DSM from the point cloud. To contrast, Survey will ultimately derive a TIN, or a Triangular Irregular Network from the point cloud. Survey will first perform an outlier filter and terrain filter on the point cloud before generating a grid of points. Once you are happy with the classification then you can generate the TIN. In the end, both programs will generate a surface but it does so in different ways.
The problem with a TIN is the resolution isn’t the same. A DSM uses the GSD (usually around 3.2cm for me) whereas a TIN uses the Grid of Points (which I can only get down to .7m grid spacing) resulting in a lower resolution surface.
Here’s a rough screenshot of the difference I can see.
Hi DroneLink,
I brought this issue up with our developers and it has generated some interest. Unfortunately I do not have an immediate solution. I would highly suggest posting in the feature request category for PIX4Dsurvey. This is closely monitored for interest amongst topics.
Thanks for that feedback, and the workflow that you use! As Mike said, its an interesting question, and we’re looking at it on the development team. We can certainly shorten the number of steps by quite a lot if we enable a raster output of the current TIN and a min resolution equal to the GSD. You would lose sharpness in the output from breaklines that you have - would that tradeoff be OK for you?
Thanks for the reply. I think anything to shorten the workflow will be useful. As far as the loss in sharpness from breaklines; are you referring to the setting in the TIN processing options, or the physical breaklines in the elevation of the collected surfaces? If the former, that does not affect my use case.
As to the latter, that would definitely be a downside to me. I deal with slopes under 2%, therefore the precision is key. That’s essentially the reason I found this issue in the first place. The TIN in its current state is not precise enough for my projects.
Thanks for the input, and I look forward to your response.
Following this with interest as we are in a similar position. needing a DSM from the Point Cloud. I Have been taking the Point cloud from Matic then into Survey for editing then I use GlobalMapper to produce the DSM from the edited Point Cloud. The better option would be to just have Geoid support in Mapper.
@mpower we’re working towards having a simple point cloud editing tool in PIX4Dmatic, so that you can edit it directly in PIX4Dmatic and generate the DSM based on that.
Good news folks, the point cloud editing was added in version 1.50 of PIX4Dmatic. Select polygon selection in the menu bar, then select the area, right click to delete.
I just tried using the clipping box to remove some unwanted noise from the point cloud (some people who were standing around at the time of the survey), after I did this and switched off the clipping box to view all the data I had I had selected a whole load of data that I wanted.
I’m noticing a bug where if I select points and try to delete them while a separate project is processing, nothing happens. The points do not get deleted.
@Mike_K@Pierangelo_Rothenbuhler Recently revisited this topic, and have found the point cloud editing in 1.5 to be helpful. I have mostly migrated to Matic and Survey as a result.
However there a still a few annoying things that could be improved.
Why does matic not have a terrain filter option?? There is the new object selection tool, but that is not helpful for my uses. And as far as I know, there is not a way to filter in survey, and bring the pointcloud back into matic. Just being able to import pointclouds would fix this, and be generally very useful.
And there is still no support for tilled exports like in mapper. Currently have to export tiff/png and use other software to generate tiles.
@DroneLink thanks for the feedback, regarding your points:
PIX4Dsurvey is the terrain workflow tool that follows what you created in PIX4Dmatic. Can you clarify why you’d like to bring the filtered point cloud back into PIX4Dmatic? That said, we may look into adding point cloud import in PIX4Dmatic later this year.
As for the “tilled exports”, do you mean making tiles of a geotif for example? or what do you mean? Here is how you can create them in PIX4Dmatic, either directly in the exports at the end of the processing panel:
or under File > Exports > Orthomosaic:
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