Re: Worldmap mercator projection - Latitude to Y calculation.

On 2026/1/17 7:19:55, R.Wieser wrote:
> John,
> 
>>> Did you _try_ using just the tangent on a couple of places?
> ...
>> I have to do some more experiments.
> 
> After having done so, it looks like that
> 
> tan(DegToRad(Latitude)*0.78)\2.53627
> 
> gives a nice result.

Asssuming DegToRad() just means multiply by pi / 180 ...

[]

> By the way, 0.78 is rather close to Pi/4 .  Somehow that raises my suspicion 
> that that is the actual value to be used, and my 0.78 is caused by my "that 
> looks good" eyeballing ...
> 
> Regards,
> Rudy Wieser
> 
> 
... then the above simplifies to tan(Latitude*pi*pi/720)\2.53627, and of
course pi*pi/720 can be given as a constant.

-- 
J. P. Gilliver. UMRA: 1960/<1985 MB++G()ALIS-Ch++(p)Ar++T+H+Sh0!:`)DNAf

"Tolerating intolerance is not a virtue." - Barry Shein