[mapserver-users] World file creation

[Brent Fraser]

Jeff,

Most of us let a client-side (browser) JavaScript library like 
OpenLayers handle the screen <-> projection calculation (among a lot of 
other things).  have a look at GeoMoose (http://www.geomoose.org) as a 
framework to bring together the server-side and client-side components.

Best Regards,
Brent Fraser

On 7/5/2012 4:13 PM, Jeff Lake wrote:
> Thanks for the reply ...
> Lets ask this ..
> I am setting up an open source weather mapping application (php)
> I already know most of my target audience will not be able to install
> MapServer and or proj4.
> I have been trying to get a handle on various map projection's.
> decided to use 3
> Grid (or flat non-projected)
> Mercator
> and Lambert Conformal Conic
>
> The first 2 was easy enough creating the needed Classes
> to convert Lat/Long to screen pixel X/Y
>
> Lambert has me lost ... every script I have found
> be it C, perl, python, or php all return me  X/Y in meter's
>
> but for the life of me .. I cannot or have not found the magic
> formula to convert the meter's to screen X/Y
>
> I have looked at gPoint, PHPproj4, but they all go no further
> then meter's (or it at least seems like it)
>
> -Jeff Lake
> MichiganWxSystem.com
> WeatherMichigan.net
> TheWeatherCenter.net
> GRLevelXStuff.com
>
> On 7/4/2012 9:31, Brent Fraser wrote:
>> Jeff,
>>
>>   World files use projected x/y coordinates.  Use the Proj4 library 
>> functions (in Mapscript)  to project the upper left and lower right 
>> spherical lon/lat coordinates to x/y, then use the image size 
>> (length, width)  to calculate the values for the world file 
>> (http://en.wikipedia.org/wiki/World_file)
>>
>> Best Regards,
>> Brent Fraser
>>
>> On 7/3/2012 8:27 PM, Jeff Lake wrote:
>>> Maybe I'm not searching on the correct terms.
>>> But what is the magic formula for creating world files ??
>>>
>>> I have a map of the US with the following projection info
>>> ullat=53.3638
>>> ullon=-130.964
>>> lrlat=18.2977
>>> lrlon=-69.1058
>>> sp1=0
>>> sp2=39
>>> cm=-95.5
>>> rlat=36.5
>>> width=640
>>> height=480
>>> projection=lambert
>>>
>>> now how on earth do you figure the meter per pixel??
>>> prefer php, but guess I could convert
>>>
>>
>>
>>
>>
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>
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