Re: Dislocated Mercator Projection

Hi Orlando,

You might want to run OpenMap with a -Ddebug.shape java flag set to let
the shape layer print out what it thinks is going on.

The ShapeLayer uses a SpatialIndex file that it creates (.ssx), to let
it know the bounding box rectangles for each graphic. The DMS
coordinates of the shape file may be affecting what gets displayed on
the screen at that scale. You might have to (delete and) remake the ssx
file.

- Don

On Sunday, March 24, 2002, at 01:57 PM, orlando feitosa wrote:

> Hi Don,
>
> Thanks for your help, I changed the original ESRIPoly.read method
> before the degToRad call, to the following:
>
> radians[i+1] = ((float)readLEDouble(b, ptr));//x (lon)
> aux = ((int) radians[i+1]);
> radians[i+1] = ((((radians[i+1] - aux) * 60) / 100) +
> aux);
> // System.out.println("LON: " + radians[i+1]);
> radians[i+1] = ProjMath.degToRad((float)radians[i+1]);
> ptr += 8;
>
> radians[i] = ((float)readLEDouble(b, ptr));//y (lat)
> aux = ((int) radians[i]);
> radians[i] = ((((radians[i] - aux) * 60) / 100) + aux);
> // System.out.println("LAT: " + radians[i]);
> radians[i] = ProjMath.degToRad((float)radians[i]);
> ptr += 8;
>
> and the map projection appears in right coordinates, SOLVING the
> problem with all my Shapefiles, but another problem begun related to
> the SCALES.
> When the scale is around 600,000 or greater (Zoom out) the Map is
> displayed on the screen correctly, but when I try to Zoom in the
> projection, the Map just disappears from the screen.
> I tried to find other related classes or methods involved with this
> change, but I havenít any success.
> Do you have an idea how to solve the new problem?
>
> Thank you so much for attention.
>
> 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: Mon, 18 Mar 2002 19:25:12 -0500
>>
>> 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,
>>>>>
>>>>> IÃm 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?
>>>>>
>>>>> IÃll 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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