Compute GCP values for gdal_translate in a PNG image

Question

I am using the incorrect GDP for gdal_translate based on gdlainfo command line since image is offset from correct location. Image is at correct location when I use QGis GeoReference using my clicked on corners which are not the same as I used when using the command line gdal_translate. How do I translate the GCP corners to the correct values?? I need to automate my georeferencing.

Command Line Call:

gdalinfo --> Upper Left (0.0, 0.0) Lower Left (0.0,10434.0) Upper Right (11242.0,0.0) Lower Right (11242.0,10434.0) Center ( 5621.0, 5217.0)

gdal_translate -of GTiff -gcp 0 10434 43.0 11.0 -gcp 11242 10434 44.0 11.0 -gcp 0 0 43.0 12.0 -gcp 11242 0 44.0 12.0 myimage.png myimage.tif

gdalwarp -s_srs EPSG:4326 -t_srs EPSG:4326 myimage.tif myimage_2.tif

QGis Call that Works:

gdal_translate -of GTiff -gcp 1001.19 202.821 43 12 -gcp 10826.7 180.285 44 12 -gcp 978.659 9983.29 43 11 -gcp 10826.7 10028.4 44 11 myimage.png myimage_2.png

gdalwarp -r near -tps -co COMPRESS=NONE myimage_2.png myimage.tif

Answer 1

My png image had white space around the edges which caused my GCP offset problem. A full answer to plotting a "density" map and generating tiles can be found at https://stackoverflow.com/questions/35185554/generate-density-plot-of-big-data-set-to-overlay-in-google-maps