Problem During Step 3 WHile Creating NDVI Map

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi,

I’m getting the following warning during step 3 processing:

Warning w9020: GDAL Warning <1> RowsPerStrip not defined … assuming all one strip.

The error multiplies a few hundred times and step 3 does not finish processing. I’m trying to create a reflectance map using NDVI Images taken by a Parrot Sequoia. The other steps process just fine and tiles for the different colour bands have been created but not merged.

Does anyone know why this problem occurs?

2

Hi Kieran,

The warning shouldn’t matter. The reason the reflectance map is not merged might be because you did not check merge tiles.

Do you get any error in the log file? It would be great if you can create a ticket in support and also attach the log file and p4D file.

3

Hi, thanks for your reply.

I definitely chose “merge” tiles. I also chose a few other options that didn’t finish processing either, like google tiles.

The error mentioned above also comes up in the log file so I will create a ticket and add the log file and the p4d file.

4

That would be great. The warning shouldn’t cause any problem. We can figure out once we get your log file.

5

Hi, I have the same problem. So, if there is any solution how to fix it, please post here. Thank you.

6

Hi,

The warnings shouldn’t cause any problem. I suspect it might be due to oblique images (maybe the area had slopes or the flight wasn’t nadir). Ag template uses alternative calibration which assumes that the images are nadir. I would suggest you use standard calibration and re-process. If that does not solve your issue, you can file a support ticket to us.

7

Hi again,

I managed to get an NDVI image by selecting “generate NDVI image” (if I recall correctly) on the right hand side after processing the last step (and getting those warnings).

The reultingimage looked perfect and I thought the matter was resolved. However, this week my colleague tried to analyse the image in ArcGIS and we noticed that the image seemed to lack the actual index values. Any idea how this happened? 

8

Hi Kieran,

What values does ArcGIS show? They should have the same values that were displayed in Pix4D. If some pixels have missing values, it is because those pixels were overexposed.