Blank images when processing NDVI

Apps / Services
1

I’m getting blank images during the process of retrieving NDVI for certain lands!

You can follow the link that includes all needed payloads for HTTP requests and endpoints:

2

Hi there @yasserakbbach !

I tried repeating the process and get one of the dates which you do the request for, so all good until that point.

In the Process API request you make a request on a geometry. Is there a reason why you didn’t use the bbox bounds like in the dates request?

If I change the bounds part of the payload to:

"bounds": {
            "properties": {
                "crs": "http://www.opengis.net/def/crs/OGC/1.3/CRS84"
            },
            "bbox": [34.3749669970627, -5.89915791677634, 34.3781915977676, -5.90363203995753]
        },

where I use the same bbox info as you provide in the dates request, then I get a non-null image:

image
image855×850 20.3 KB

This probably points in the direction that your geometry+crs combo isn’t what you expect it to be.

Cheers,
Matic

3

Hello @matic.lubej,
Thank you for your input, the main reason why I’m sending geometry instead of bbox is the fact that I need to render the responded image on a polygon on a mapbox (Android) as shown on the figure below:

NDVI.PNG
NDVI.PNG454×785 92.7 KB

The bbox way will return a squared image, while geometry returns exactly the same sent polygon dimensions!

4

Hi,

OK, I understand your motivation to use geometry. Thank you for the explanation.

I see you are using CRS84, which should be similar to WGS84, with the exception of reverse coordinates (using lon/lat instead of lat/lon).

However, it doesn’t seem to me that the geometry you are using corresponds to the bounds of the original bbox you used in the beginning. I plotted both geometries with the appropriate CRS, but the two don’t overlap in the least bit.

I suggest you first make sure that you are using a geometry which corresponds to your original bbox.

Cheers

1 Like
5

Yeah this is what I figured out too, I’ll double check and return back to you.
Thank you for your time!

6

Hello again @matic.lubej,

Finally I managed to fix the issue, thanks for your help I really appreciate it.
There were two problems on my side (as you stated):

  1. I was mistakenly using some sort of static geometry.
  2. I’ve been using wrong order lon/lat instead of lat/lon for the bbox.

Regards.

1 Like