private void initTransformations() throws Exception {
//compute final world to grid
// base grid to world for the center of pixels
final AffineTransform g2w;
if (!request.isHeterogeneousGranules()) {
final OverviewLevel baseLevel = rasterManager.overviewsController.resolutionsLevels.get(0);
final OverviewLevel selectedLevel = rasterManager.overviewsController.resolutionsLevels.get(imageChoice);
final double resX = baseLevel.resolutionX;
final double resY = baseLevel.resolutionY;
final double[] requestRes = request.spatialRequestHelper.getComputedResolution();
g2w = new AffineTransform((AffineTransform) baseGridToWorld);