Re: Upper and Lower Latitudes ...

Hi Pradeep,

On Thursday, September 6, 2001, at 11:12 AM, PRADEEP RAMACHANDRAN wrote:

> Thanks Don,
>
> But isn't the Viewer app showing 360 degrees across ?

I would have expected it to, but upon looking into it, the CADRG
projection min scale is limited to a pixel ratio. I can't remember why
it's written differently than the Mercator projection, but think it has
to do with the CADRG projection being pixel/degree based, and those
ratios are specified in the RPF specification. It was written to
support RPF raster charts, so probably wasn't intended to provide a
whole earth look.

> And by trying to make the window square like it, assumes
> more of the look CADRG projection for the default height, width
> for the viewer app, even lesser area appears to be covered ?

But the mercator projection is working as expected, no?

- Don

>
> Regards,
> Pradeep.
>
> --
>
> On Thu, 6 Sep 2001 10:40:32
> Donald Dietrick wrote:
>> Hi Predeep,
>>
>> The upper/lower bounding that you are seeing may be a result of the
>> projections limiting the minimum scale to whatever allows only 360
>> degrees across the map window. If you make the window more
>> square-like,
>> more of the latitudes will appear.
>>
>> - Don
>>
>> On Wednesday, September 5, 2001, at 09:34 AM, PRADEEP RAMACHANDRAN
>> wrote:
>>
>>> Hello,
>>>
>>> The differene between the upper and lower latitudes for
>>> both Mercator and CADRG projections seem restricted to
>>> be within a certain range viz., approximately 135 degrees,
>>> with the min. scale.
>>>
>>> To simulate this the map center for the OpenMap viewer
>>> application was set to 0,0. The upper/lower bounding
>>> latitudes for the min scale ( 207,476,976 for Mercator and 389,940,928
>>> for CADRG ) were less than 70/-70 respectively.
>>>
>>> Is this the normal behaviour for OpenMap ?
>>>
>>> Regards,
>>> Pradeep.
>>>
>>>
>>>
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>>
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Donald F. Dietrick, dietrick@bbn.com
BBN Technologies, 10 Moulton Street, Cambridge, MA 02138
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>>
>
>
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