geotiff/geotiff-stats

Get Statistics from a Large GeoTIFF while Using a Low Amount of Memory

geotiff-stats's Issues

Add support for quantiles and standardDeviation

I've been doing something similar in my geotiff-server. The other stats I found happy for colour balancing were quantiles at 2% and 98%, and the standard deviation

In my code it looked something like

import {min, max, quantile, standardDeviation} from 'simple-statistics'

function getBasicStats (arr) {
  var filtered = arr.filter(function (element) {
    return element !== -999
  })
  return {
    percentiles: [quantile(filtered, 0.02), quantile(filtered, 0.98)],
    min: min(filtered),
    max: max(filtered),
    stdDeviation: standardDeviation(filtered)
  }
}

Cannot find module 'geotiff/dist/compression'. Possible incorrect path.

Thanks for your work on this, this module has saved me a lot of work in a project!

I'm not sure the require path is correct in index.js

Changing const { getDecoder } = require('geotiff/dist/compression'); to const { getDecoder } = require('geotiff'); works for me.

Add options: optionally skip calculating of min/max via tiling

Sometimes people will want to try to grab the min/max value from the GDAL_METADATA (if it exists), but won't want to wait to get the min/max by grabbing every tile from a COG's overview or raw data if no overview exists. (This can take roughly 15 seconds for Landsat overviews).

Here's a possible API solution:

const { bands } = getStats(image, { quick: true });

Alternatively, a user could specify what percentage of tiles to sample (defaulting to 1.00 for 100%). In the following example, we sample roughly 50% of the tiles:

const { bands } = getStats(image, { sampleSize: 0.5 });

If a user doesn't want to sample any tiles, they can use:

const { bands } = getStats(image, { sampleSize: 0 });