Re: Dislocated Mercator Projection

Hi Orlando,

If that is the problem, then you can make some modifications to the
shape layer package code that reads the data files, and modify them
before they are used to create OMGraphics. For the
com.bbn.openmap.layer.shape package, you can look in the ESRIPoly.read
method, making the modifications before the degToRad() call (and so on,
for each shape type you are trying to display).

The com.bbn.openmap.DMSLatLonPoint could help you with the conversion,
but you'd have to do the parsing to load it properly, and you'd also
want to keep one in the ESRIPoly to reuse for every coordinate, instead
of allocating one for every coordinate.

Hope this helps,

Don

On Monday, March 18, 2002, at 04:21 PM, orlando feitosa wrote:

> Hi Don,
>
> Thanks for your answer, I¥m starting OpenMap with the scale=230.000
> and I tried to zoom in until scale=7.187 and zoom out until
> scale=920.000, but the dislocation of the map as whole keeps the same.
>
> Talking with Mr.Alexander, he noticed the following:
> ___________________________________________________________________
> -23.576 --> -23 0.576*60 = -23 34.56
> -46.745 --> -46 0.745*60 = -46 44.7
>
> The guess was that you were trying to compare Lat, Lon in decimal
> degree with coordinates in Degree.Minute form. What I did is just
> converted fractional part of degree to minutes.
> Just double check this. Probably everything works fine and you don't
> need any correction
> ____________________________________________________________________
>
> ....the problem is that, I must do something!!!! I don¥t know where and
> how I can adjust the projection in the right coordinates (slide up the
> map).
>
> This information should helps, for each Shapefile *.shp there is a file
> called *.prj with following lines:
>
> &REM Clark 1866 Lat/Lon, Degrees, -180 ==> +180
> &REM LL
> PROJECTION GEOGRAPHIC
> UNITS DD
> PARAMETERS
>
> Thanks for any help.
>
> Best Regards,
>
> Orlando
>
>
>
>> From: Don Dietrick <dietrick@bbn.com>
>> To: "orlando feitosa" <snapsurf@hotmail.com>
>> CC: openmap-users@bbn.com
>> Subject: Re: Dislocated Mercator Projection
>> Date: Sun, 17 Mar 2002 16:06:33 -0500
>>
>> Hi Orlando,
>>
>> What scale is the map that you are looking at? Does the error decrease
>> when you zoom in? You may be seeing the effects of rounding that the
>> projection is doing at smaller scales, setting a pixel's coordinates to
>> some value, while rounding other lat/lon values to that closest pixel
>> as
>> well.
>>
>> - Don
>>
>> On Saturday, March 16, 2002, at 10:50 PM, orlando feitosa wrote:
>>
>>> Hi Friends,
>>>
>>> IÌm having a problem with the Mercator Projection, when a map (a
>>> Shapefile) is rendered using the ShapeLayer, all the projection
>>> appears dislocated in a wrong LAT/LON coordinates.
>>>
>>> Here are differences in a specific coordinate:
>>>
>>> Wrong Projection Should be Difference in Decimal Degrees
>>> LAT -23.576 -23.346 -230
>>> LON -46.745 -46.445 -300
>>>
>>> Is there a kind of adjustment parameter to setup this dislocation?
>>>
>>> IÌll appreciate any help.
>>>
>>> Best Regards,
>>>
>>> Orlando
>>>
>>>
>>> _________________________________________________________________
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>>>

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, dietrick@bbn.com
BBN Technologies, Cambridge, MA
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
>>
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>
>
>
>
> _________________________________________________________________
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>
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