[Geomoose-users] Dealing with scales

Thu Jun 20 06:54:31 PDT 2013

Hello Jim,

In the mapbook I have the following params:

            *<param name="projection">EPSG:2263</param>*
* <param name="max_extent">1115163,61542,1581609,527988</param> *
* <param name="initial_extent">1115163,61542,1581609,527988</param>*
* <param name="always_scroll_zoom">true</param>*
* <param name="measure_tool.show_area_segments">false</param>*
* <param name="layer_controls.metadata.on">false</param>*
* <param name="group_checkboxes">true</param>*
* <param name="default_tab">Catalog</param>*
* <param name="ground_units">ft</param>*
* <param name="maxResolution">156543.03390625</param>*
* <param name="numZoomLevels">20</param>*
* <param name="reference_map.enabled">false</param>*
* <param name="coordinate_display.usng">true</param>*
* <param name="fractional_zoom">true</param>

*I added the *<param name="ground_units">ft</param>* following your advice
and it is almost perfect (1:43157 GeoMoose and 1:448286 Chameleon);

One thing I noticed in Firebug. Although I can see the layers, I get two
errors (atually, one - 2 times):

*GET EPSG2263.js 404 NotFound (/geomoose/libs/proj4js/lib/defs/EPSG2263.js
was not found on this server)
*

On Thu, Jun 20, 2013 at 4:13 PM, Jim Klassen <klassen.js at gmail.com> wrote:

> It looks like CONFIGURATION.ground_units is simply being passed into
> OpenLayers as OpenLayers.Map.units.  The scale combo-box is using
> OpenLayers.Map.getScale.
>
> The OpenLayers page [1] says it supports feet, but indicates the parameter
> is only used if it is not defined in the projection.  What projection do
> you have set in the configuration section of your mapbook?  Alternatively,
> what do the following three lines output from Firebug (or other javascript
> console) while viewing your GeoMoose site?
>
> ====
>
> Map.getProjection();
>
> Map.units;
>
> Map.getProjectionObject().proj.units;
>
> ====
>
> Digging up my old county coordinates example... Proj4js doesn't seem to
> recognize units=sft.  Map.units = "m" and proj.units = "null".  If I set:
>
>         <param name="ground_units">ft</param>
>
> Then Map.units="ft" and the initial scale changes from 1:6933504 with
> meters to 1:2113331 with feet (a factor of ~ 3.28 which is what would be
> expected).
>
> [1]
> http://dev.openlayers.org/docs/files/OpenLayers/Map-js.html#OpenLayers.Map.units
>
> On Jun 20, 2013, at 2:46 AM, Robert R. Raiz wrote:
>
> 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*
>>>>>
>>>>>
>>>>>
>>>>>  _______________________________________________
>>>>> Geomoose-users mailing list
>>>>> Geomoose-users at lists.osgeo.org
>>>>> http://lists.osgeo.org/mailman/listinfo/geomoose-users
>>>>>
>>>>>
>>>
>>>
>>>  --
>>> *Raiz Roland Robert*
>>>
>>>
>>>
>>>
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>
>
> --
> *Raiz Roland Robert*
>
>
>
>

-- 
*Raiz Roland Robert*
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