Recognizing the difference in perspective of the left and right eyes, he began by making line drawings of each eye's view of simple objects. (scientificamerican.com)
This may mean a return to geographic districts, with results that will depend on residential patterns and the politics of line drawing in particular cities. (educationnext.org)
One technique known to be of effective is to begin with a sheet of paper that has two vertical lines drawn from top to bottom. (breedingbetterdogs.com)