[Geomoose-users] Dealing with scales

[Robert R. Raiz]

Hello all,

Did some more research on this and I would point out a few aspects.

I tested with the demo files and there, it all seems ok. The thing is, in
the demo shapefile, we have the data in meters and so is the mapbook.xml
file configured. eg: *<param name="ground_units">m</param>*.

All my shapes, projections, all the data I have is in feet. I guess this is
the problem as I don't think there is a ground_units param for feet (only *‘m’,
‘in’, ‘mi’, ‘dd’*).

The only place where I found something related to feet was in the
\geomoose\htdocs\php\print.php file which deals with the print option:

*if($ground_units == 'ft') {*
* $inches_per_unit = 12.0;*
* }*

Really close to the difference I gave as an example in my first post (1:448286
- Chameleon and in GeoMoose I have 1:35203 for the same extent);
448286/35203 =~ 12,7

As I am not a developer (but would like to be sometime in the future), I
would need some guidelines as to where I could add/modify/update the
ground_unit param (eg: *<param name="ground_units">ft</param>*) so GeoMoose
could treat correctly the feet unit of measurement and have a correct
scale. I think it would be a huge enhancement for this to be supported as
especially US data is kept mostly in projections using feet.

I really appreciate all the feedback received,


On Wed, Jun 19, 2013 at 9:30 PM, James Klassen <klassen.js at gmail.com> wrote:

> I second that.  Even feet vs meters should only be a factor of 3.  My
> experience is GeoMoose scales are close to but not exactly the same as
> MapServer scales (when DPI is left as defaults).  I haven't tried a site
> using feet lately, but I know it used to work (the first GeoMoose site was
> in feet.)
>
> I'm sorry I am too swamped right now to dig into this further at the
> moment.  Hopefully someone else on the list can help you more.
> On Jun 19, 2013 11:07 AM, "Brent Fraser" <bfraser at geoanalytic.com> wrote:
>
>>  Since the difference in the reported scale between Chameleon and
>> Geomoose is over an order of magnitude, I suspect there is a units
>> mis-configuration somewhere.  Just where depends on which reported scale is
>> closer to what's expected...
>>
>> Best Regards,
>> Brent Fraser
>>
>> On 6/19/2013 9:37 AM, Robert R. Raiz wrote:
>>
>> Hello James,
>>
>> Well, yes, actually for me it is important to know that the  MINSCALE /
>> MAXSCALE from map files will be read accordingly in GeoMoose. I need the
>> correspondence between them to be correct and to be able to check the
>> correct rendering of features.
>>
>> I tested today and it seems what I have in the lower right part
>> (GeoMoose) is not quite ok compared to what I have in the mapfile (I am
>> only referring to scale here);
>>
>> To sum up, seeing the big difference between the scales in Chameleon and
>> GeoMoose at the same extent, I do not understand how this could work. To
>> give a short eg: I have a class rendered in the mapfile between MINSCALE
>> 2000 and MAXSCALE 6000. How can see this range (class) in GeoMoose if I
>> cannot rely on the scale in the bottom right corner.
>>
>> Hope I am not missing something here :)
>>
>>
>> On Wed, Jun 19, 2013 at 6:08 PM, James Klassen <klassen.js at gmail.com>wrote:
>>
>>> Not really since the browsers don't accurately report screen DPI, so
>>> traditional scales in the interactive map are rather meaningless.  The main
>>> place the scale is important is to allow printing to a known scale.
>>> Assuming GeoMoose's DPI matches MapServer's (and I think it is at least
>>> close), it also helps when setting min/max scale denominators in MapServer
>>> layers/classes.
>>>
>>> The scale reported in the interface (in the drop down in the lower
>>> right) is a scale assuming some nominal display DPI.  (Either 72, 75 or 96
>>> I think, but would have to check to be sure.)
>>>
>>> The scales parameter in the mapbook is actually a resolution.  (It is
>>> simply passed into OpenLayers to setup the zoom levels, primarily for the
>>> popular tiled basemaps.)
>>>  On Jun 19, 2013 9:41 AM, "Robert R. Raiz" <raizrobert at gmail.com> wrote:
>>>
>>>>  Oh, as usual, I find something right after I post..
>>>> I read that "The scales are actually ground units per pixel resolution
>>>> settings and not true scales. "
>>>>
>>>> Is it possible to somehow change this to render actual scales?
>>>>
>>>>
>>>> On Wed, Jun 19, 2013 at 5:33 PM, Robert R. Raiz <raizrobert at gmail.com>wrote:
>>>>
>>>>> Hello all,
>>>>>
>>>>> As I said in a previous post, I am trying to replace the old Chameleon
>>>>> web mapping tool with GeoMoose.
>>>>>
>>>>> Something that I did not quite understand, is why the scales are
>>>>> different in these two mapping tools if they have the same extent;
>>>>>
>>>>> So, I have an extent in the mapfile. Chameleon is giving me a scale
>>>>> of 448286 and in GeoMoose I have 1:35203
>>>>>
>>>>> Can you please tell me what am I missing? I first thought that it has
>>>>> something to do with the ground_units param (as I need the units in feet);
>>>>>
>>>>> Thank you,
>>>>> --
>>>>> *Raiz Roland Robert*
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>  --
>>>> *Raiz Roland Robert*
>>>>
>>>>
>>>>
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>>>>
>>
>>
>>  --
>> *Raiz Roland Robert*
>>
>>
>>
>>
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-- 
*Raiz Roland Robert*
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