WMS get optimal size ratio upon defining bounding box

Question

I'm connecting with a WMS and saving a cropped map. Ideally I would like to just define the bounding box ( bbox ) and define either the height or width of the output image in pixels, to get the correct height/width ratio. However, I'm getting errors if I define the height or width. It's working when I define the size of the output image

from owslib.wms import WebMapService

url = 'https://rasterdata.hunzeenaas.nl/erdas-iws/ogc/wms/Rasterdata?service=WMS&request=getmap'
wms = WebMapService(url)

img = wms.getmap( layers='Luchtfoto_2015_Ortho_25cm_RGB_voorjaarsvlucht'],
                  styles=['default'],
                  srs='EPSG:3857',
                  bbox=(72865, 7022456, 730231, 7023717),
                  size=(1000,1000),
                  format='image/jpeg',
                  transparant=True )
out = open('output.jpg', 'wb')
out.write(img.read())
out.close()

How do I get the correct image size ratio, while defining the bounding box?

Answer 1

I don't know how generic this answer is, but it looks like the correct width/height ratio can be read from the bounding box of the WMS. Correcting the size of the output image with this ratio will lead to the desired result