# What's relationship between pixel spacing and resolution?

Let's take as an example the `Sentinel-1` SAR satellite for which data is accessible online.
The `pixel spacing` in the `range` and in the `azimuth` are found inside the `xml` files bundled with the product. But I need the `resolution` instead.

For a `level-1 SLC` product, the spacings are given as:

``````<rangePixelSpacing>2.329562e+00</rangePixelSpacing>
<azimuthPixelSpacing>1.396573e+01</azimuthPixelSpacing>
``````

But, how do I calculate the `resolution` based on the knowledge of the`Pixel Spacing`?

• It's a rectangular pixel, not square, so there are two resolution values: 2.3 by 13.9. Commented Aug 26, 2015 at 17:36
• @mkennedy you mean that the `resolution` = `pixel spacing`? (I know that the `resolution` is not the same in the `range` and in the `azimuth`, that's why there are two `pixel spacing` values). Commented Aug 26, 2015 at 17:48
• Have a look here: SAR Sentinel-1 resolutions Commented Aug 27, 2015 at 1:53
• Not entirely sure, perhaps this will help you understand. Commented Aug 27, 2015 at 13:37
• Thanks for the link. I understood that the `pixel spacing` is different from the `resolution` although they're related. Besides, the `pixel spacing` is also related the `sampling rate`. Commented Aug 27, 2015 at 22:41

Based on my own understanding:

In SAR images resolution and pixel spacing are two different things.

Resolution means the maximum ability to distinguish two close scatters. The resolution of one SAR image is usually based on the bandwidth of signal (in Range direction) and the 'synthetic bandwidth' in azimuth direction.

Well Pixel spacing is easier, it just means in your SAR image, what does one pixel correspond to meters in real world.

Pixel spacing usually does not equal to resolution. It is usually slightly bigger. This is because the images we can get are usually resampled again before they are delivered to you.

So you don't calculate resolution based on pixel spacing, you calculate them based on other parameters such as bandwidth and etc.

• Your two definitions correspond with what's written here: sentinel.esa.int/web/sentinel/user-guides/sentinel-1-sar/…, although they defined the `pixel spacing` as the distance between `adjacent pixels` in `meters` instead of the size of a pixel in meters (as you defined it). Commented Aug 31, 2015 at 19:32

The ground range resolution = ((pixel spacing in range)/sin(incidence angle))