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.