assigner vs renderer

assigner

noun
  • One who, or that which, assigns. 

renderer

noun
  • One who, or that which, renders. 

  • A software or hardware process that generates a visual image from a model. 

  • A vessel in which lard, tallow, etc., is rendered. 

How often have the words assigner and renderer occurred in a corpus of books? (source: Google Ngram Viewer )