[mapserver-dev] Resolution dependent issues

[thomas bonfort]

Tamas,
I think we should be doing something similar to what we do for normal
map draws, i.e. if you pass a request for dpi=72&width=50&height=50
you should get a visually very similar image to what you get with
dpi=144&width=100&height=100 once that second image has been rescaled
down by 50%.
My issue with #5035 is that you're returning an image that has a
different size than what the width=..&height=... url parameters
requested. I do think that the scalebar sizes, margins, keysize,
keyspacing, etc... should be adjusted automatically (i.e. the tests
that fail in #5035 will still fail until the autotests are updated to
remove the "map.legend=keysize+40+40" CGI commands, as that would be
done automatically)

thanks for looking into this.

regards,
thomas

On 15 February 2015 at 21:48, Tamas Szekeres <szekerest at gmail.com> wrote:
> Hi Devs,
>
> Not too long ago, I wanted to address the issue when drawing legend and
> scalebar on high resolution images, but it looks like I've run into a couple
> of discrepancies in the concept, which would require further discussion.
> This is where we are now:
>
> 1. When drawing high resolution images we will set up the resolution factor
> (resolution/defresolution) greater than 1 and will increase the image size
> accordingly. This causes that the symbol sizes lines widths are increased
> proportionally so as to provide the same look of the map image at the
> greater size. But the issue is that this is not the case with the embedded
> scalebar and legend sizes and the related parameters. Therefore I wanted to
> modify the scalebar/legend drawing code to increase the size related
> parameters (like scalebar sizes, margins, keysize, keyspacing etc.)
>
> 2. However according to a recent discussion here I might think that we would
> want to keep the user specified sizes (like legend keysize) not to grow
> proportionally with the resolution factor(?) That means if the user
> specifies the keysize as an 50x50px image that should be always the same
> pixel size at all resolutions. (On the contrary we let the specified symbol
> sizes to grow)
>
> I'm curious to know what folks do think here (ie. which sizes should grow
> and which not), before taking any further actions.
>
> Thanks,
>
> Tamas
>
>
>
> 2014-11-05 21:50 GMT+01:00 Lime, Steve D (MNIT) <Steve.Lime at state.mn.us>:
>>
>> Thanks for taking these on. I agree that the goal was to get the same look
>> across resolutions for all map components.
>>
>>
>>
>> From: mapserver-dev-bounces at lists.osgeo.org
>> [mailto:mapserver-dev-bounces at lists.osgeo.org] On Behalf Of Tamas Szekeres
>> Sent: Wednesday, November 05, 2014 2:27 PM
>> To: mapserver-dev at lists.osgeo.org
>> Subject: [mapserver-dev] Resolution dependent issues
>>
>>
>>
>> Hi Devs,
>>
>>
>>
>> I've added 2 issues related to the resolution setting in MapServer.
>> According to RFC-55 we expect to get the same look of the map when setting
>> the image size and the resolution to higher values to get a higher
>> resolution (printable) image. But this is not the case for the scalebar and
>> legend according to:
>>
>>
>>
>> https://github.com/mapserver/mapserver/issues/5029
>>
>>
>>
>> And I've also found a problem related to the OGR auto styling, see:
>>
>>
>>
>> https://github.com/mapserver/mapserver/issues/5028
>>
>>
>>
>> I undertake to rectify the problems, if no one has objections about the
>> way they should work.
>>
>>
>>
>> Best regards,
>>
>>
>>
>> Tamas
>
>
>
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