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Volume Difference of an Area Surveyed Over Different Time Periods

Hi

I read the article about volume differences of an area surveyed over different time periods, but I assume this is about single stockpiles, correct?

What if the customer wants to have an answer about a specific area of the gravel pit in regards to how much material has been added or extracted?

To be more specific:
https://sway.com/5jBpgLIBIjrG3VQr

We have a clear understanding of the topology of the gravel pint surveyed (April 2015) in the above link.

Now in September 2015, the customer wants to now, how much material has been added to a defined area of the gravel pit and how much material has been added to the total gravel pit.

So the topology measured this April would be used as a zero reference and material on top of this reference would be defined as material added to the gravel pit and we need to know, how much this will be.

Thank you,
Martin Hämmerli

You should use other software for volumetric change detection on the site. I think,Pix4d does not has the volumetric comparisons. You might use GIS packages…

Bests.

Hi Martin,

Soon, we will have new tools that permit an easy and user-friendly comparison of volumes. This is something to come in future versions of the software.

The current solution we give is the following:

Let´s say that you want to know the volume difference of an area that was mapped in April (Project 1) and in September (Project 2).

  1. Process the two project with GCPs, so that you have the same good georeference. For more information: https://support.pix4d.com/hc/en-us/articles/202557489-Step-1-Before-Starting-a-Project-4-Getting-GCPs-in-the-Field-or-Through-Other-Sources-optional-but-recommended-

If you do not have GCPs, you can mark some points in Project 1 and take the coordinates that Pix4Dmapper calculates for these points. Then you should add as GCPs the same points in project 2 (using the coordinates that you already took from project 1). Then, the two projects will be perfectly aligned. The above mentioned procedure is better explained here: https://support.pix4d.com/hc/en-us/articles/204373409 .

Draw a volume object in Project 1: https://support.pix4d.com/hc/en-us/articles/202560319-How-to-draw-a-New-Volume-with-the-rayCloud .
Now you have the volume of this object / area in Project 1.

Export the volume object: Right click on the volume object in the rayCloud > Export.

Then open Project 2 and import the volume object: https://support.pix4d.com/hc/en-us/articles/202558089#label5 .

Now you will have the volume of this object / area in Project 2.

Comparing the two volumes you will get the difference of volume for this area.

We hope that this solution will help you and more of our users!
Regards,

any news on automated change detection over time? we are looking to do follow ups on different projects, and following the steps described by Pix4D on this post for every building, road, tower, stock piles would take forever. 

Should we still use QGIS or other GIS software after getting the orthomosaic, point cloud, etc. from Pix4D in both images (before and after)?

Yes would like this feature for measuring changes over time, not just volume, but changes to features. An overlay type where you overlay the second project over the first and changes are identified.

If I want volumes now I run and measure as individual projects, but now I need to identify surface changes.

I dont have GIS software!

Cheers

Hello Peter,

Thank you very much for your feedback, is very much appreciated. We have registered your suggestion and we will consider for future releases. 

You can also try the open source GIS software: QGIS. 

Best Regards, 

Global Mapper could be the best couple hundred dollars you ever spent. Forgive the expression, but it is the Swiss Army knife of the geospatial community. You can perform a stunning array of post processing of Pix4D outputs. Raster, vector, DEM, las, analysis, etc.