PIX4D FIELDS - TIFF Files with a wrong Geo reference

Agriculture General Ag Questions/Troubleshooting
1

I exported some VARI TIFF files and when I tried to upload them to my SRES, it gives a wacky geo reference 0.0000457, -96.1548639421. Is there a way to change the geo reference for the TIFF file?

2

Hi Edward, all of the raster files created by Pix4Dfields have an UTM local projection.  I am not familiar with SRES however if you wish to change the projection and datum this is possible in third party software such as QGIS.  This functionality is not available in Pix4Dfields itself. 

Regards, Sam

3

Is the UTM local projection based on the information given by the uploaded files, or it is a random location picked by Pix4D?
The SRES Plot Management System is reading a location that is not even close to the actual location of the plot we scanned.

4

 

Pix4Dfields export GeoTIFF files in a “Local Transverse Mercator” coordinate system.

This is like UTM (Universal Transverse Mercator), but using different parameters to get a better precision locally. 

 

https://en.wikipedia.org/wiki/Transverse_Mercator_projection#Coordinates,_grids,_eastings_and_northings

They are:

Central Meridian (φ0 in wiki page): we use the longitude of the first image. This makes that every field is near the central meridian, doing all the measurements more accurate.

Scale Factor (k0 in wiki page): because we are near the central meridian, we use a value of 1. That gives us a better accuracy.

False Easting and Northing (E0 and N0 in wiki page): This values are used in UTM just to avoid negative coordinates (that is understandable in the 40’s). We set the to the position of the first image. That produces coordinates with small values (the size of the field), but may produce negative values (south or west of this reference).

 

The issue is most likely that SRES Plot Management System is interpreting such information incorrectly from our images (i.e. it reads the local transverse mercator as the UTM and this produces issues).  I hope this is of some help explaining why you have negative values.  If you would like to send over images for us to check further please raise a support ticket and we would be happy to help.

Regards, Sam

5

Hi Tim, I hope you can help me here. I have a large field mapped and did all the index availables, when exporting, QGIS shows me that are in WGS84 transverse mercator. Is there a way to have it on UTM instead? Thanks

6

Hi Federico,

This is from our release notes: “Universal Transverse Mercator (UTM) is the coordinate system used for the orthomosaics (instead of Transverse Mercator) for better interoperability with other software.”

Can you send us the map so that we can check it from our side? You can upload it in google drive and share the link here.

7

Thanks @Momtanu, here’s the dropbox link: NDVI https://www.dropbox.com/s/cvry886rlwsmn68/NDVI.data.tif?dl=0
Mosaic: https://www.dropbox.com/s/0lby75bxv8ixn63/Orthomosaic.tif?dl=0
please do not use in publications or online posts, it’s a recent job and cannot be shared. Thanks

8

Hi Federico, 

 All of the raster files created by Pix4Dfields should have UTM local projection. Can you also forward me the quality report of the project? 

9

Thanks Kapil. Have no Q report, was done in Fields

10

Hi Federico,

All of the raster files created by Pix4Dfields should have UTM local projection. Did you try to open the result with other third-party software which might have changed the coordinate system? Can you upload the images on the Pix4D cloud and process it?