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I'm creating and saving the NDVI output of MOD13Q1 of a given district to Google Drive from Google Earth Engine.

If I use the following code, the output tiff gets generated, but it is shifted about 14 KM to the north.

(The shift is not present in the Image shown on the map, but only in the Tiff file that is created)

var modis=ee.Image('MODIS/006/MOD13Q1/2018_09_30')
  .select(['NDVI', 'sur_refl_b03']);                     

var vi = modis.expression(
    '(BL >1500)?0:((A==-3000)?0:(A*0.0001))', {
      'A': modis.select('NDVI'),
      'BL':modis.select('sur_refl_b03')
});   

var geometry = ee.Geometry.Rectangle([79.5, 20.4, 81.8, 21.7]);   

Map.setCenter(80,20.5, 8);    
Map.addLayer(vi, {min: -1, max: 1, palette: [
    'FFFFFF', 'CE7E45', 'DF923D', 'F1B555', 'FCD163', '99B718', '74A901',
    '66A000', '529400', '3E8601', '207401', '056201', '004C00', '023B01',
    '012E01', '011D01', '011301'
  ]});   

Export.image.toDrive({
  image: vi,
  description: 'Gondiya_NDVI_30Sept',
  scale: 250,
  region: geometry,
  fileFormat: 'GeoTIFF',
  formatOptions: {
    cloudOptimized: true
  },
  maxPixels: 1e12
});

What is causing this shift? How do I correct this?

2

This could be a GEE bug exporting to MODIS sinusoidal projection, I'm not sure. but, a fast workaround is to export to a different CRS:

Export.image.toDrive({
  image: vi,
  description: 'Gondiya_NDVI_30Sept',
  scale: 250,
  crs: 'EPSG:4326',
  region: geometry,
  fileFormat: 'GeoTIFF',
  formatOptions: {
    cloudOptimized: true
  },
  maxPixels: 1e12
});

Obviously, you can select a better CRS than WGS84 long/lat regarding your needs.

With original code: enter image description here

With a CRS specification: enter image description here

|improve this answer|||||
  • do you know the EPSG code for MODIS sinusoidal is? I'm trying to display my geotiffs in QGIS but cannot find the proper projection? or how can I display these in the right spot? – Derek Eden Feb 20 at 15:35
  • 1
    @DerekEden this is code projection: spatialreference.org/ref/sr-org/modis-sinusoidal if you can’t view it correctly, change manually CRS to above one – aldo_tapia Feb 21 at 1:35
  • thanks...had to add this as a custom projection then was able to manually set the projection – Derek Eden Feb 21 at 13:21

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