[Geomoose-users] Scalebar & Measure

Dan Little danlittle at yahoo.com
Thu May 27 11:45:40 EDT 2010 

Probably just make it the default setting inside of the tools.


----- Original Message ----
> From: Brent Fraser <bfraser at geoanalytic.com>
> To: Len Kne <lkne at houstoneng.com>
> Cc: "geomoose-users at lists.sourceforge.net" <geomoose-users at lists.sourceforge.net>
> Sent: Thu, May 27, 2010 10:02:01 AM
> Subject: Re: [Geomoose-users] Scalebar & Measure
> 
> Good.

   Should we just hard-code it within Geomoose (as below), or 
> provide a 
configuration parameter in the mapbook?

Brent

Len 
> Kne wrote:
> Very nice!  Worked great and is much simpler than the 
> way I was doing the calculation.  
> 
> Len
> 
> 
> -----Original Message-----
> From: Brent Fraser [mailto:
> ymailto="mailto:bfraser at geoanalytic.com" 
> href="mailto:bfraser at geoanalytic.com">bfraser at geoanalytic.com] 
> 
> Sent: Wednesday, May 26, 2010 1:53 PM
> To: Len Kne
> Cc: '
> ymailto="mailto:geomoose-users at lists.sourceforge.net" 
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net'
> 
> Subject: Re: [Geomoose-users] Scalebar & Measure
> 
> Len(and 
> others interested in measuring),
> 
>    Here's my 
> solution to the measure problem:
> 
> In main.js somewhere around 
> line 138 add the two lines below marked with a "//BWF":
> 
> 
>     Tools['measure'] = new 
> 
> OpenLayers.Control.GeoMooseMeasure(OpenLayers.Handler.MeasurePath, 
> 
> measureToolOptions);
>     Tools['measure'].geodesic = 
> true;  //BWF
> 
>     Tools['measurearea'] = new 
> 
> OpenLayers.Control.GeoMooseMeasure(OpenLayers.Handler.MeasurePolygon, 
> 
> measureToolOptions);
>     
> Tools['measurearea'].geodesic = true;  //BWF
> 
> 
> Thoughts?
> 
> Brent
> 
> 
> Brent Fraser 
> wrote:
>> Paul, Len,
>>
>>    Our scale 
> problem is a (mostly) map projection issue.  All map projections 
> 
>> introduce distortions in trying to represent a round(ish) Earth on 
> a flat plane. 
>>   Mercator is no different: it is like wrapping 
> an up-right cylinder around the 
>> Earth, projecting light from the 
> center onto the cylinder 
>> 
> (http://en.wikipedia.org/wiki/Mercator_projection).  As you can imagine the 
> 
>> distortions get "worse" the further from the equator.   The 
> distortions can be 
>> modeled as a Point Scale Factor.  At the 
> equator the Point Scale Factor is 1.0, 
>> at latitude 60 degrees North 
> (or South), the scale factor is 0.5!
>>
>>    So 
> what's the solution?  Here's mine:
>>
>>    1. 
> Enhance Proj4 (and Proj4js) to return the Point Scale factor (given the 
> 
>> projection and a location)
>>    2. Enhance 
> MapServer and Openlayers to use the Point Scale Factor in 
>> 
> calculating distances and scale.
>>
>> I'm trying to drum up 
> interest, but so no takers....
>>    
> http://osgeo-org.1803224.n2.nabble.com/Point-Scale-factor-service-td4938743.html
>>  
> 
>> 
> http://osgeo-org.1803224.n2.nabble.com/Re-3265-Scale-dependent-layer-switching-error-with-Mercator-td4966902.html
>>
>> 
> Best Regards,
>> Brent Fraser
>>
>> Len Kne 
> wrote:
>>> The scale bar issue with the web Mercator projection is a 
> limitation of 
>>> OpenLayers, the application GeoMOOSE 2.x uses to 
> render the map frame. 
>>>   There has been discussion on the 
> OpenLayers site about providing a 
>>> patch (this link offers a 
> patch http://trac.openlayers.org/ticket/1890 ) 
>>> in the next 
> version 2.9.  I'm sure GM will upgrade to OL 2.9, but not 
>>> 
> sure there is any schedule in place to do 
> this.
>>>
>>>  
>>>
>>> The 
> cursor issue is also kind of fun because it seems each browser 
>>> 
> handles the custom icons differently.  Here's the attribute in the 
> 
>>> mapbook which defines the query for the Identify 
> service:
>>>
>>>  
>>>
>>> 
> cursor="url('cursors/identify2.cur') 9 
> 9,url('cursors/identify2.cur'),auto"
>>>
>>>  
> 
>>>
>>> This makes three attempts to draw the cursor, 
> the first offsets the 
>>> mouse click 9 pixels from the top and the 
> left.  Firefox can use this 
>>> value and seems to line the 
> mouse click up pretty good with the 
>>> crosshair.  However, 
> IE cannot handle the offset adjustment, so it reads 
>>> the second 
> cursor definition.  There are tools like AT File Mole which 
> 
>>> can be used to edit the hotspot of a cursor.  Attached is 
> the latest 
>>> version I have been using for Identify service, 
> again this seems to line 
>>> the crosshair up pretty well with the 
> mouse click.  If you are using 
>>> Safari or Chrome, these 
> setting don't seem to work at all and I would 
>>> recommend not 
> using customer cursors with those 
> browsers.
>>>
>>>  
>>>
>>> 
> Len
>>>
>>>  
>>>
>>> 
> *From:* Wirth, Paul [mailto:
> href="mailto:Paul.Wirth at kniferiver.com">Paul.Wirth at kniferiver.com]
>>> 
> *Sent:* Saturday, May 01, 2010 9:03 PM
>>> *To:* '
> ymailto="mailto:geomoose-users at lists.sourceforge.net" 
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net'
>>> 
> *Subject:* [Geomoose-users] Scalebar & 
> Measure
>>>
>>>  
>>>
>>> 
> Two questions:
>>>
>>>  
> 
>>>
>>> 1.       I have a web Mercator 
> application, and I noticed that the 
>>> scalebar does not display 
> the correct distance.  For instance, when the 
>>> scalebar 
> shows a distance of 20 miles, it measures only 13.8 miles.  I 
> 
>>> know the measure tools are working correctly, so I assume this 
> is a 
>>> scalebar issue.  Any thoughts on how to fix 
> this?
>>>
>>> 2.       I think this 
> question was asked before, but I can't seem to 
>>> find it on the 
> e-mail list.  With the measure tools, the cursor does not 
>>> 
> start measuring at the "crosshairs" when the user clicks, but rather in 
> 
>>> the NW quadrant of the crosshairs.  Is there a way to 
> change it so the 
>>> measure start point will be on the 
> crosshairs?
>>>
>>>
>>> 
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