Accuracy

Donatas_Azaravicius · August 31, 2015, 5:24am

Hi.
Using Trimble UX5 drone I have collected photos of pit site and processed it with Pix4Dmapper Pro Trial, UASMaster Lite and Agisoft photoscan Pro.
Report from Pix4D http://www.filedropper.com/krivaiciaireport

Point cloud files was imported in AutoCAD Civil 3D software. And TIN surfaces was
compared. Most of site was in 1-3 GSD accuracy, but not all. Location on a slope have up to 4 meter difference. And it was steep slope. So, accuracy depends on the steepness of the slope? And how much it depends?

I have processed photos using Pix4Dmapper Pro few times and compared results. Got the same results as comparing Pix4Dmapper results with other software results.

So if I process photos with Pix4Dmapper Pro many times with same settings I will get different results? Different in flat location will be 1-3 GSD and in steep slopes will be big?

Julie_Pichon · October 21, 2015, 2:11pm

Hello Donatas,

Could you please directly attach the Quality Report to this post? We couldn’t get it from your link.

The error of 1-3 times the GSD in the vertical direction (1-2 times the GSD horizontally) only applies to projects having GCPs.
Is that your case?

Besides the overlap, GSD, image geotaggs, and GCPs, the visual quality of the images also impacts on the accuracy.
For instance good lightning conditions, clearness i.e. without blur, but also in terms of content, e.g. sharp edges, reflective surfaces, certain type of roads and rooftops may present lower accuracy locally.

If you are not satisfied by the reconstruction of some 3D points in your model, like in steep slope areas, you could add Manual Tie Points (MTPs) in order to locally improve the accuracy: https://support.pix4d.com/hc/en-us/articles/202560349

More about accuracy and precision of the outputs: https://support.pix4d.com/hc/en-us/articles/202558889

Best regards,

Niti_Mishra · March 1, 2017, 5:57pm

Hi Donatas and Pix 4d support:

I am trying to use Pix4d mapper pro to processes photos acquired from Trimble UX5 HP UAS. The photos iself do not have geotags as the geotags are stored in a separate file. This is thus different from analyzing photos acquired by DJI drones.

I am wondering if there is a document or online reference that I can look up on how to process ux5 hp data with Pix4d?

Thank you!

Julie_Pichon · March 3, 2017, 10:43am

Hi Niti,

It is possible to import a geolocation file when there is no geotag written in the image EXIF. Just make sure the file complies with the Pix4D format requirements. More information: https://support.pix4d.com/hc/en-us/articles/202558539

Regards,

d_barbova · March 6, 2020, 10:21am

Hi all,

I am trying to process a flight from Trimble UX5 HP on Pix4d. I have the same problem with missing photos geolocation. I struggle to find a separate file containing GNSS information. I know it can be exported from TBS but no longer have a licence for it.

I`m wondering if Niti know where this file should be stored?

Thank you!
Darina

teodora.enache · March 6, 2020, 11:38am

Hi Darina,

If the images do not contain the GPS metadata, then you could first process them in the Trimble Aerial Imaging software, which will generate a CSV file that has the latitude and longitude of the photos. However, in the case of Trimble UX5 HP, Trimble Business Center might be needed. It might be that TBC can generate the image geolocation file in a format compatible with Pix4Dmapper (CSV).

As Julie said, you can import in Pix4Dmapper a geolocation file when there is no image geotags (read this article here: https://support.pix4d.com/hc/en-us/articles/202558539).

Hopefully this helps.

Cheers,
Teodora

Donatas_Azaravicius · March 6, 2020, 12:47pm

Hi,
had not used TBS in years so, can’t say anything about it, but if it is the same as before, here are no file with GNSS information if you had not exported it before.
But I wander if you really need photos geolocation information? Photos geolocation information lets you ease select photos with GCP points, but you can do it even if you don’t have geolocation information. And geolocation information lets process photos faster, but result will not be best if you don’t have GCP points at all. So if you have GCP points, you don’t really need geolocation information to get good results.

d_barbova · March 10, 2020, 1:24pm

Thank you very much for your help.
I managed to proceed the data using only GSPs, it does take a while but the results are satisfying.

Best regards,

Darina