Automated geospatial image mosaic generation with multiple zoom level support
Generation of a plurality of orthomosaic image layers for a geographical area, wherein the layers comprise different spatial resolutions and are radiometrically normalized to facilitate improved radiometric consistency when zooming relative to the geographic area. In applications that facilitate zooming with respect to a geographic area imaged by the orthomosaic layers, radiometric normalization of the orthomosaic image layers may reduce radiometric discontinuities when zooming in, zooming out, and/or panning a displayed portion that is output to the user. The orthomosaic layers may be generated based on one or more orthomosaic image layer or may be developed independently using a source images. In any regard, the radiometric normalization may include generating a normalization function based on image metadata that is calculated and may be independent of the spatial resolution of the image.
1. A method for creation of a plurality of mosaic layers of a mosaic image for different zoom levels of a geographic area covered by the mosaic image, comprising:
first generating a first mosaic image layer having a first spatial resolution, wherein the first mosaic image layer comprises a plurality of source geospatial images; and
second generating at least a second mosaic image layer having a second spatial resolution that is of a lower spatial resolution than the first spatial resolution, wherein the second mosaic image layer comprises downsampled versions of the plurality of source geospatial images used to generate the first mosaic image layer;
first calculating first image metadata for at least a portion of the first mosaic image layer, wherein the first image metadata is independent of the spatial resolution of the first mosaic image layer;
second calculating second image metadata for at least a portion of the second mosaic image layer, wherein the second image metadata is independent of the spatial resolution of the second mosaic image layer;
determining a normalization function based on a comparison of the first image metadata for the first mosaic image layer and the second image metadata for the second mosaic image layer, and
applying the normalization function to at least a portion of the second image to normalize the second mosaic image layer relative to the first mosaic image layer.
2. A method according to claim 1 , wherein the first generating includes at least one of auto source selection, auto cutline generation, or radiometric normalization of the plurality of source geospatial images.
3. The method of claim 2 , wherein the second generating comprises downsampling the first mosaic image layer after generation of the first mosaic image layer.
4. The method of claim 2 , wherein the second generating comprises downsampling the source geospatial images to generate a corresponding plurality of low spatial resolution versions of the source geospatial images and the second generating includes at least one of auto source selection, auto cutline generation, or radiometric normalization of the plurality of low spatial resolution versions of the source geospatial images.
5. The method of claim 1 , further comprising: downsampling the portion of the first mosaic image layer prior to the first calculating.