[Proj] cs2cs vs. proj??

[Frank Warmerdam]

Gerald I. Evenden wrote:
> A question has arisen in my mind as to what is the difference between the 
> programs cs2cs and proj?  What does one do that the other does not?
> 
> On the surface the names would imply that one deals with transforming data 
> between datum systems, which may include projections as a suboperation, and 
> the other would deal with only cartographic projections.

Gerald,

This is essentially the case, yes.  The cs2cs program uses the
pj_transform() functions which includes support for datum shifts,
prime meridian shifts and goes from one coordinate system to another.

The proj program on the other hand is largely unchanged from the
original, uses pj_fwd() and pj_inv() and does not support any
of the extended capabilities of pj_transform().

> Obviously, as I am painfully aware, this is not the case.

I'm not sure why you think this is not the case.

Best regards,
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