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Discussion on volume calculation

I have several doubts related to volume calculation

1.Does we need GCP foe more accurate volume determination ? and Normal geottaged images in geographical cooradinates is enough for reliable results between 90-95% of accuracy which gives better result ?

2.Does trail version of pix4d gives wrong result compared to actual volume of the pile.

3.I have calculated volume in pix4d and global mapper it gives large difference in both the results?

4.Give me any suggesion i need to achieve 90-95% of accuracy in volume calculation.what are the steps i want to follow 

Please suggest me…

 

Hello,

If geotagged images are used and the volume measurements are supposed to be computed for small areas, GCPs are not required for accurate volume measurements. However, if volumes have to be calculated for large areas, GCPs are required for accurate measurements.

When calculating the volumes, the vertices of a base have to be marked in at least two images in order to calculate the error. Additionally, it is important to select the right settings for the base that fit your purpose. Step by step instructions how to draw a volume can be found in the following article 202560319 and description of settings can be found here 208652926.

If the same base is used in both Pix4Dmapper and Global Mapper for volume measurement, the difference in values should be minor. It is possible to export the base from Pix4Dmapper which can be imported to Global Mapper. For more information: 211245943.  

To achieve accurate volume measurements we recommend to have high overlap between images, sharp images, well distributed GCPs, Manual Tie Points (MTPs), etc.

For more information about:

Additionally, please note the Trial version has full capabilities of the software.

Best regards,

While generating Orthomosaic i am getting error in merging tiles. I have generated 30 tiles so need to merge please suggest me a solution to merge

Hi vijayaraghavan R, please create a new post with your new question. This makes it easier to find and discuss a topic. Thank you. 

Hello Pierangelo Rothenbühler

please define “small” area. Is 100 acres of stockpile a small area ?

Hi Jerry,

I would not say that 100 acres is a small area for a stockpile. Did you already try to compute volumes for your project? Do you have GCPs?

hello Julie… thank you for your reply…

 

 

Hello Julie. How many acres are considered a small area?

Im calculating volume in areas around 4 acres. I would have to use GPC?

Hi Tomas,

 

GCP’s are always welcome in a project no matter the size of it. Not having GCP’s would impact differently a project where you have RTK or PPK rather than in a regular GPS information project. To better understand the accuracy of the outputs please see:  202558889

You will have to understand what exactly is your comparison baseline. Do you compare two volumes for two projects without GCP’s or you compare one with a GCP’s vs. no GCP’s etc…

Best,

Ina

I am flying a 50 acre stock yard that has several piles ranging from 2000 cubic yards to 20,000 cubic yards, flying it with a matrice 200 with a zenmuse x5s focal length 15mm. I have 5 permanent ground control points surveyed in with a Leica GS14. The gcp’s are just around the perimeter of the stockyard at varying elevations. I have surveyed the piles in by hand at very tight intervals and my volumes are coming back 10-13% off. When I check the elevations in point cloud the toe of the piles are usually spot on with the Leica survey but the top of pile elevations are anywhere from 2-3 feet off. I have checked and double checked my camera setting, I am getting great pixelated pictures with no blur or rolling shutter and the ortho comes back clear. I have tried almost everything I can think of, any suggestions or thoughts on these issues? Thanks

Hi Luke,

After reading the description of the issue, I could not see any major issues in the workflow you follow. The “top of pile elevations are off” could be related to the way the dataset was acquired. 

The DJI camera has the rolling shutter  that can be an issue for the reconstruction depending on the flight conditions ( low height of the flight, high speed of the drone ) and the area that is mapped. My go-to solution in these cases would be to:

  • Enable the linear shutter optimization in the Image Properties Editor.
  • Capture the project area again while flying slower and/or higher to reduce the amount of linear rolling shutter distortion that is present in your images. 

Could you give it a try with the linear rolling shutter enabled and let me know if this solves the issue?