how to measure the dimension or distance from the relevancy maps?

Hi
Is is t possible to use Nerfstudio viewer to know the distance/dimension of the relevancy maps?
Let me use the image below as an example, the sponge is highlighted in the relevancy maps, but how could I get the rough dimension of the sponge?

<img width="734" alt="image" src="https://github.com/kerrj/lerf/assets/33056320/0d15a4ae-592b-4313-8e3e-d5ff70b9a5d3">
