title: Proper storage of a uniform, XYZ plane, in Postgres PostGIS
body: <p><strong>Problem Statement</strong>:
  Consider a gray scale image taken of a plane. Each pixel is an intensity value (Z).
  I have the position in physical space of the top left most pixel. I also have the offset of each X and Y pixel from left to right (X), and up to down (Y). Consider the image to be perfectly non-distorted, so the offset is uniform for every row. </p>
  
  <p>I would like to store these image in a POSTGIS database in a way that allows the user to query a polygon from an image. </p>
  
  <p><strong>Current Implementation</strong>:
  Currently I believe I am doing something stupid, I create a Multipoint geometry and store each point with ( X Y Z ) using python. Since the image is uniform, I am repeating lots of data (x and y for each point), but this works when querying the database for a polygon, but is an excessive amount of extra data.</p>
  
  <p><strong>Question</strong>:</p>
  
  <ol>
  <li>What is the best way to store such data and allow the user to query
  a polygon from the image? </li>
  <li>Is PostGIS Geometry the correct datatype?</li>
  <li>Is the multipoint approach reasonable? </li>
  </ol>