[mapserver-users] Use of palette file: Problems with changingcolors when tiling

[Espen Isaksen]

Yes, we know, but we just tried to bypass the problem by fooling
Mapserver. And that did not work :-) That was just a test, which might
show that Mapserver is filling in some Mapserver defined color in the
waterlayer when it shouldn't.

Espen


2009/10/29 Stephen Woodbridge <woodbri at swoodbridge.com>:
> The correct usage of the palette file is to NOT fill it up with 256 colors.
> What you want to do it get all the colors that you explicitly reference in
> the mapfile and place them in the palette file. then mapserver will initiate
> you file with these colors. Then when you antialias something mapserver will
> use the remain color slots and fill them with the antialiased generated
> colors.
>
> -Steve W
>
> Espen Isaksen wrote:
>>
>> No, that color is not present in the mapfile or in the palette.txt
>> file. We use the color 108 189 243 on lakes.
>>
>> This is happening on other features(with other colors) for us as well.
>>
>> I did test to fill up the palette file with the same colors more than
>> one time in order to get 256 colers in the file and that actually
>> fixed the problem. However, it created all other kind of problems with
>> the colors, especially with anti-aliasing on labels.
>>
>> Espen
>>
>>
>>
>> 2009/10/28 Steve Lime <Steve.Lime at dnr.state.mn.us>:
>>>
>>> Is the color 125,202,228 (the water value in the image on the left) used
>>> in your mapfile?
>>>
>>>>>> On 10/28/2009 at 5:25 AM, in message
>>>
>>> <a4cd3760910280325l4c4a1feah93782aeb259462d2 at mail.gmail.com>, Espen
>>> Isaksen
>>> <espen.isaksen at gmail.com> wrote:
>>>>
>>>> Hi!
>>>>
>>>> We are testing out using a palette file in our outputformat to
>>>> decrease file size in the png output. Most of the time this works
>>>> great, but some times when we are tiling the data we get some errors.
>>>> The color seem to shift to a similar color from one tile to another.
>>>>
>>>> We have added the colors we use in the map file in the palette.txt
>>>> file. The documentation says it needs 256 colors in the map file, but
>>>> we do not use that many colors right now. (we tried adding the same
>>>> color more than one time, but that created other problems....)
>>>>
>>>> I have attached a png file showing the problem across a lake. The
>>>> color on the right side is the correct color and the color we have
>>>> added to the palette file. The color on the left side of the lake is
>>>> not something we have set.
>>>>
>>>> I have also added the palette.txt file and the outputformat we use is
>>>> this:
>>>>
>>>>         OUTPUTFORMAT
>>>>                        NAME             "png"
>>>>                        DRIVER           "AGG/PNG"
>>>>                        MIMETYPE         "image/png"
>>>>                        IMAGEMODE        "rgb"
>>>>                        EXTENSION        "png"
>>>>                        FORMATOPTION     "PALETTE_FORCE=TRUE"
>>>>                        FORMATOPTION     "PALETTE=/data/maps/palette.txt"
>>>>                 END
>>>>
>>>> Does anybody know why this happens in Mapserver and how to fix it?
>>>>
>>>> Espen
>>>
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>
>