[Proj] Beginner Question: Latitude/Longitude to x, y conversion - understanding output

AdamDynamic helloadamdynamic+proj4 at gmail.com
Mon Feb 24 08:30:12 EST 2014

Ah ok, thanks for that. Reading your answer, the notation makes a bit more
sense (a risk of using something you find on the internet without actually
understanding it)

> To output the map onto 900x1100 rectangle you have to scale the length
> and width of your projected map coordinates to 900 and 1100. And then
> you have to apply shift of origin of course.

Am I correct in thinking that as I have the latitude of true scale as the
Equator, then no shift of origin is required?

In terms of scaling the output, my understanding is that the 'corners' of a
projection based on latitude and longitude should be -180,-90 and 180,90 -
when I convert these values using the PyProj library I get values of 1E30
for each value (which seems to me clearly wrong). What is the best way to
scale the output in terms of min/max values (in 'pseudo-meters') for each
corner of my 900x1100 rectangle?

Thanks again for the help!


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