RDA Template Images can't decode some image tiles from RDA

[drwelby]

import os
os.environ["VIRTUAL_RDA_URL"] = "https://rda-dev.geobigdata.io/v1"
from gbdxtools import RDATemplateImage
img = RDATemplateImage('04f10eb3b38fab7c4a81923b527580e9b779815772481174465f9a8cdc05e6fa', 'Orthorectified_Pauli', calibration='sigma0')
win = img.randwindow((500,500))
win.compute()

Error is occuring here:

https://github.com/DigitalGlobe/gbdxtools/blob/master/gbdxtools/rda/fetch/threaded/libcurl/easy.py#L55

arr = imread(temp.name)

imread can't figure out the pixel mode, and is throwing the error 'unknown pixel mode'

[drwelby]

Looks like imread can't decode RDA tiles when:

• there is no extension
• the file is a 32 bit tiff

CatalogImage tiles are fetched with a .tif extension, RDATemplate images have no extension.

If the tile has a .tif extension then imread will use the tifffile plugin, which can read 32-bit tiffs. If there is no extension, then it uses imageio which then fails.

Some possible solutions:

• switch the backend to something that can decode correctly
• add the extension, assuming we know what it is
• sniff the extension
• try to decode, if we hit this error try again and assume it's a tiff

The problem is hinted at here:

https://github.com/DigitalGlobe/gbdxtools/blob/master/gbdxtools/rda/fetch/threaded/libcurl/easy.py#L46

with a TODO that didn't

[drwelby]

Modifying the tile reading to:

try:
    arr = imread(temp.name)
except SyntaxError:
    arr = imread(temp.name, plugin='tifffile')

seems to work. The question is can template nodes return tiles of other image types, and whether imageio can decode them.

[drwelby]

Need to look at sniffing the mimetype of the image

[drwelby]

RDA returns mimetypes for all tiles, so we'll use that to pick the appropriate image loading plugin:

https://github.com/DigitalGlobe/gbdxtools/tree/ISS-727-template-tiles

[drwelby]

Manually merged to 0.16.7

[drwelby]

This error also returns the odd error about Error code: 200; in 0.16.5 the error message is misleading.

There is a workaround for 0.16.5 and earlier versions:

from skimage import io
io.use_plugin('tifffile', 'imread')

This forces the fetcher to use the tifffile plugin to decode the tiff tiles.