[Geomoose-users] Scalebar & Measure
Dan Little
danlittle at yahoo.com
Thu May 27 12:12:18 EDT 2010
Is there ever a reason why geodetic would be avoided (besides the compute cost in doing the math). Also, I'm vehemently against adding arbitrary parameters to the XML definition.
----- Original Message ----
> From: Brent Fraser <bfraser at geoanalytic.com>
> To: Dan Little <danlittle at yahoo.com>
> Cc: Len Kne <lkne at houstoneng.com>; "geomoose-users at lists.sourceforge.net" <geomoose-users at lists.sourceforge.net>
> Sent: Thu, May 27, 2010 11:11:14 AM
> Subject: Re: [Geomoose-users] Scalebar & Measure
>
> How about omething like:
<tool name="measure"
> title="Measure" type="internal" action="measure"
> geodesic="false"/>
<tool name="measurearea" title="Measure Area"
> type="internal" action="measurearea" geodesic="false"/>
Note the
> default would be true so the implementer would need to turn it off if they
> wanted distances on the mapping plane.
Hmm. Does this imply I could
> have both geodesic AND map measures at the same time by creating these tools as
> well:
<tool name="measure2" title="Measure Ground Dist"
> type="internal" action="measure" geodesic="true"/>
<tool
> name="measurearea2" title="Measure Ground Area" type="internal"
> action="measurearea" geodesic="true"/>
Brent
Dan Little
> wrote:
> Probably just make it the default setting inside of the
> tools.
>
>
> ----- Original Message ----
>> From:
> Brent Fraser <
> href="mailto:bfraser at geoanalytic.com">bfraser at geoanalytic.com>
>>
> To: Len Kne <
> href="mailto:lkne at houstoneng.com">lkne at houstoneng.com>
>> Cc:
> "
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net"
> <
> href="mailto: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:
> href="mailto:bfraser at geoanalytic.com">bfraser at geoanalytic.com"
> href="mailto:
> href="mailto:bfraser at geoanalytic.com">bfraser at geoanalytic.com">
> 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:
> ymailto="mailto:geomoose-users at lists.sourceforge.net"
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net"
> href="mailto:
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net">
> 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:
> href="mailto:Paul.Wirth at kniferiver.com">Paul.Wirth at kniferiver.com">
> ymailto="mailto:Paul.Wirth at kniferiver.com"
> href="mailto:Paul.Wirth at kniferiver.com">Paul.Wirth at kniferiver.com]
>>
> *Sent:* Saturday, May 01, 2010 9:03 PM
>>>> *To:* '
>>
> ymailto="mailto:
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net"
> href="mailto:
> href="mailto:geomoose-users at lists.sourceforge.net">geomoose-users at lists.sourceforge.net">
> 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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>>>>
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