feat(geotiff): Consolidate helpers for GeoTIFF images.

[manzt]

No description provided.

[ibgreen]

Looks good, just added suggestions.

@kylebarron We should add some actual GeoTIFF tests.

[ibgreen]

Nits:

• Since the function is called fromBlob can the type be the more general Blob instead of File?
• I assume we could also accept ArrayBuffer and just call new Blob([arrayBuffer]) (or new File(...))?

[manzt]

I think you are correct, and it can be more general Blob. There is a fromArrayBuffer constructor as well: https://geotiffjs.github.io/geotiff.js/global.html

I'm not sure if you have an opinion on how to include these different global constructors in loaders.

[ibgreen]

I am thinking about it. FWIW:

• loaders.gl is currently standardized on parse(ArrayBuffer) and parseInBatches(AsyncIterator<ArrayBuffer>).
• loaders.gl/core automatically converts from other types (File, Blob, Response, ...) to those types before calling the loaders.

[manzt]

That makes sense. However, I think the fromArrayBuffer method is for TIFF images that fit into memory (e.g. fromArrayBuffer(fetch('https://data.ome.tiff').then(res => res.arrayBuffer()))). The other sources are intended for large, multichannel/tiled TIFFs, where different byte-ranges are read dynamically.

[manzt]

Perhaps, similar to Zarr, there would be a way to create a GeoTIFF source using loader.gl utils/modules: https://github.com/geotiffjs/geotiff.js/tree/master/src/source

[kylebarron]

• loaders.gl is currently standardized on parse(ArrayBuffer) and parseInBatches(AsyncIterator<ArrayBuffer>).

What do we do for large tilesets like i3s and 3dtiles? It seems a similar issue here where we don't want to bring the entire tileset into memory.

[kylebarron]

Note there are even some instances where you want to pass multiple URLs to fromURLs to create a single file, for example with a Landsat or Sentinel scene where there are 10 or 11 different files and you might want to load 3 of them.

[manzt]

Note there are even some instances where you want to pass multiple URLs to fromURLs to create a single file, for example with a Landsat or Sentinel scene where there are 10 or 11 different files and you might want to load 3 of them.

I don't think it fits very well in the loaders.gl paradigm, but allowing for loadGeoTIFF to take any GeoTIFF object (regardless of source), enables the flexibility for tiff storage/layout (similar to allowing for a zarr.Store).

[kylebarron]

I don't think it fits very well in the loaders.gl paradigm, but allowing for loadGeoTIFF to take any GeoTIFF object (regardless of source)

Note this matches my suggestion here to avoid unnecessary fetches of the metadata. Essentially we'd have two loaders, a GeoTIFFMetadataLoader and a GeoTIFFLoader. The GeoTIFFMetadataLoader would fetch only the metadata of the GeoTIFF: here calling fromUrl, fromBlob, etc and returning a GeoTIFF object. The GeoTIFFLoader would either use the metadata/GeoTIFF object passed in or call the GeoTIFFMetadataLoader on the input.

This approach makes it possible for advanced users to load multiple tiles in succession while only loading the metadata once. Of course a similar approach is possible for Zarr as well.

[manzt]

Definitely something Analogous for Zarr as well. Given the .zarray metadata (JSON) and a valid store, you can initialize ZarrArray object(s) directly. hms-dbmi/vizarr#75

[zakjan]

@manzt Looks great as a progress towards supporting generic GeoTIFF files! I tested it with a sample file generated with GDAL: 2021060212.tif.zip (GFS wind u,v speed). I'm not sure if you continue working on it? If not, I could implement loading such files.

• ImageDescription can be undefined at

  loaders.gl/modules/geotiff/src/lib/ome/load-ome-tiff.ts

  Line 9 in 0012654

  export const isOmeTiff = (img: GeoTIFFImage) => img.fileDirectory.ImageDescription.includes('<OME');

• load non-OME files at

  loaders.gl/modules/geotiff/src/lib/load-geotiff.ts

  Line 83 in 0012654

  throw new Error('GeoTIFF not recognized.');

  
  it seems that some code from loadOmeTiff can be extracted and reused for non-OME files

@kylebarron Do you aim for COG support from the beginning, or would it make sense to start with non-COG files first, having COG in mind?

[kylebarron]

@kylebarron Do you aim for COG support from the beginning, or would it make sense to start with non-COG files first, having COG in mind?

I believe @ibgreen is thinking of a 3.0.0 release of loaders soon, where the Geotiff and Zarr loaders are included but undocumented, so that we can continue working on them until the 3.1.0 release.

[ibgreen]

Yes my thinking is that zarr and geotiff will be a focus of loaders.gl@3.1.

Do you aim for COG support from the beginning, or would it make sense to start with non-COG files first, having COG in mind?

I would like us to support both, but getting non-COG support solid first sounds like a good approach.

The COG support will require more API consideration.