Extract GeoTIFF metadata/tags in parseData about georaster HOT 3 OPEN

hey, @kandersolar . Great question! I'll think on your proposal in the coming weeks, but wanted to let you know quick that you can access the geotiff via a "private" undocumented property on the GeoRaster object called "_geotiff", like

const georaster = parseGeoRaster(url);

const tiff = georaster._geotifff;
const img = await tiff.getImage();
img.getGDALMetadata();

I'd recommend locking your georaster version if you take this approach. I can't say if this property will exist on the next major release of georaster because it's an undocumented non-public property subject to change.

from georaster.

Thanks for pointing that out! I was loading from a pre-fetched ArrayBuffer, which I guess is why I didn't notice the _geotiff attribute (seems like it is only populated when parsing from URL?).

Using that approach does indeed work to get me the metadata I'm after. However, I then ran into other problems where the georaster object no longer had mins, maxs etc attributes, nor was I able to figure out how to calculate them myself with geoblaze. I also ran into trouble with using geoblaze.identify to extract pixel values.

Here is a slimmed-down version of what I am trying to run:

    const url = window.location.origin + "/geotiffs/" + filename;
    const georaster = await parseGeoraster(url, {}, true);
    const tiff = georaster._geotiff;
    const img = await tiff.getImage();

    console.log(img.getGDALMetadata());  // works
    console.log(georaster.mins); // undefined
    console.log(georaster.maxs); // undefined
    console.log(georaster.ranges); // undefined

Any hints what I am doing wrong?

from georaster.

Hey, that's a good catch. You're not doing anything wrong per se. It's just that the API for GeoRaster definitely needs a refresh with more customizability. I'm working on a new major version, but can't say when that would be done.

The original logic behind not calculating stats when loaded from a url was to avoid situations where we tried to calculate stats on really large geotiffs, potentially fetching hundreds of megabytes.

If you want to calculate stats, you could use geoblaze like:

import geoblaze from "geoblaze";

const stats = await geoblaze.stats("https://example.org/imagery.tif", undefined, { stats: ["max", "min", "range"] });

Feel free to create an issue on https://github.com/GeoTIFF/geoblaze/issues regarding the identify problem.

I should mention that if you prefer not to use geoblaze, you could use: https://github.com/geotiff/geotiff-stats

Lastly, I don't think we have any test data on https://github.com/geotiff/test-data where the gdal metadata includes AUTHOR and CREATION_DATE. Would you be open to contributing your geotiff to https://github.com/geotiff/test-data? That'll help increase the visibility of your test case in the ecosystem of libraries that use this test data.

from georaster.