What is the ground resolution?

[fferflo]

Hey, thanks for your great work!

The paper specifies the ground resolution to be 0.12 meters per pixel at zoom-level 20, so at image resolution 1200x1200 the images would cover an area of 144x144m^2. For example the image pXO99cAVXvovXTUqlcCO1A_satView_polish.jpg:

A screenshot from the same area in Google Maps with scale in meters and the CVACT image roughly aligned by hand shows that this image covers an area of around 68x68m^2.

That would mean the ground resolution is about 5.7cm/pixel.

Maybe I missed something? Maybe the zoom level is 21, which would put the ground resolution at ~6cm/pixel, so roughly what Google Maps shows?

Thanks for you help :)

[Liumouliu]

Hi,

Please use the following equation to compute gsd:

156543.03392 * Math.cos(lat * Math.PI / 180) / Math.pow(2, zoom).

For example,

if you set lat = -35.204202, you will get gsd = 0.1219...

If I remember correctly, there is an upsampling/super-resolution (x2) step via Google API.

But keep in mind that the ground-truth gsd is always 0.1219...

Hope that helps,

Best,
liu