Image too large to export

[daleelenteny]

Hi everyone,

While using the geemap.ee_export_image() function, I received this error:

Generating URL ...
An error occurred while downloading.
Total request size (91810140 bytes) must be less than or equal to 33554432 bytes.

Is there simply a size ceiling? Any way I can work around this, apart from chopping up the image into smaller sections and exporting them individually?

[giswqs]

The limit is enforced by GEE, there is not much geemap can do. For large files, you have to export to Google Drive. See https://geemap.org/common/#geemap.common.ee_export_image_to_drive

[iuryt]

It might help others that have the same problem, but you could chunk the region into smaller pieces and scale it according to your need.

n = 6 # resulting into n-1^2 blocks
lons = np.linspace(lonmin, lonmax, n)
lats = np.linspace(latmin, latmax, n)

objs = []
counter = 1
for lonmin, lonmax in zip(lons[:-1], lons[1:]):
    for latmin, latmax in zip(lats[:-1], lats[1:]):
        region = ee.Geometry.BBox(lonmin, latmin, lonmax, latmax)
        delayed = geemap.ee_export_image(image, filename=f"landsat{counter:05}.tif", scale=50, region=region)
        counter += 1

I know that the region can be different from a simple boundary box, but what if we implement something like this?
We could add a parameter nchunks for the number of chunks in each axis in case the region is a ee.Geometry.BBox, otherwise it would raise a warning saying that nchunks is not used.

By the way, I tried to parallelize this with dask, it ran without errors but did not download anything.

objs = []
counter = 1
for lonmin, lonmax in zip(lons[:-1], lons[1:]):
    for latmin, latmax in zip(lats[:-1], lats[1:]):
        region = ee.Geometry.BBox(lonmin, latmin, lonmax, latmax)
        delayed = dask.delayed(geemap.ee_export_image)(image, filename=f"../data/external/landsat{counter:05}.tif", scale=50, region=region)
        objs.append(delayed)
        counter += 1
dask.compute(objs)

[giswqs]

See https://book.geemap.org/chapters/07_data_export.html#exporting-images. Geemap has several ways for exporting large images

[giswqs]

Another option is xee

https://github.com/google/Xee

[giswqs]

And https://geemap.org/workshops/SciPy_2024

[iuryt]

Another option is xee

https://github.com/google/Xee

Wow. This is a game changer! Thanks for sharing.