What does it mean to obscure something and what purpose does it serve in photography?

To make an etching the artist first coats the entire printing plate with an acid-resistant substance called a made from beeswax, asphalt, and other material. the artist then draws on the coated plate with an etching needle exposing the metal. next the plate is dipped in the plate is removed, the waxy coating removed, and the plate is cleaned, inked and printed.

Making a person for art class wich one should i use? 1.sports girl2.flower/date girl3.grudge4.super hero

Why do you think crime scene photographers take pictures of rooms where the crime did not occur?