topic Re: ScaleBar showing wrong measure in ArcGIS API for Flex Questions

ScaleBar showing wrong measure

sheebaashraf — Tue, 01 Mar 2011 03:09:42 GMT

I have dataframe is in web mercator but data is in WGS-84. But when i try to measure the distance as s distance displayed in scalebar is less. Please find the attached image

I'm using LODS as
<esri:lods>
       <esri:LOD level='9' scale='111831879881.70616' resolution='305.748113140705'/>
       <esri:LOD level='10' scale='55915939940.85329' resolution='152.8740565703525'/>
       <esri:LOD level='11' scale='27957969970.42686' resolution='76.43702828517625'/>
       <esri:LOD level='12' scale='13978984985.21343' resolution='38.21851414258813'/>
       <esri:LOD level='13' scale='6989492492.606933' resolution='19.109257071294063'/>
       <esri:LOD level='14' scale='3494746246.303683' resolution='9.554628535647032'/>
       <esri:LOD level='15' scale='1747373123.1520586' resolution='4.777314267823516'/>
       <esri:LOD level='16' scale='873686561.5760293' resolution='2.388657133911758'/>
       <esri:LOD level='17' scale='436843280.7884485' resolution='1.194328566955879'/>
       <esri:LOD level='18' scale='218421640.39422426' resolution='0.5971642834779395'/>
      </esri:lods>

Re: ScaleBar showing wrong measure

eddiequinlan — Wed, 20 Jul 2011 19:08:04 GMT

I'm having the same problem. In my case, the distances on the scale bar which is shown on the map is about 20% longer than the true distances.

I can measure distances using the esri:drawtool and geometryService and compare those distances to known distances on the map. This works great. However, when compared to the scale bar they are not close.

My extent and spatial reference are set correctly. I would think they would have to be for the geometryService to measure correctly.

Any ideas??????

thanx,
Eddie

Re: ScaleBar showing wrong measure

KenBuja — Wed, 20 Jul 2011 20:27:39 GMT

Take a look at this blog about measuring distances in Web Mercator

Re: ScaleBar showing wrong measure

eddiequinlan — Thu, 21 Jul 2011 13:51:39 GMT

Hi Ken,

Thanx for the response. I'm aware of the article and principals of projections, but i'm using State Plane coordinates (FIPS 904) and in very small areas....... ie land parcel measurements. I've seen others with the same issue. I just downloaded the latest esri api 2.3.1, but that hasn't made a difference. I'm must be overlooking something.......

Any more suggestions would be appreciated.

Thanx again,
Eddie

Re: ScaleBar showing wrong measure

BjornSvensson — Fri, 22 Jul 2011 14:59:20 GMT

Eddie, is it the ScaleBar that is showing the incorrect measurement or is it your measured line? My guess is that it is the latter...

Is it only when using state plan or do you see the same problem when using Web Mercator and/or geographic?

Re: ScaleBar showing wrong measure

eddiequinlan — Tue, 02 Aug 2011 20:45:23 GMT

Bjorn,

Sorry for the delay. I just found your response.

It's the scalebar which is incorrect. Measurements via the measure tool are correct. My map service is in state plane coordinates (wkid = 2238) overlaid with the new ESRI street map (wkid = 102100). I use to use the old street map (wkid = 4326), but it too had the same issue.

Thanx for your response,
Eddie

Re: ScaleBar showing wrong measure

MattCharton — Mon, 16 Apr 2012 20:13:54 GMT

We too are having this problem with ESRI Flex API 2.5 using Flex 4.6 (in Air 3.1).

We have a tiled basemap in wkid 3434 (NAD_1983_StatePlane_Arkansas_South_FIPS_0302_Feet). Geometry service is returning correct measurements, but the scale bar is around 3.27 times greater... it would thus seem to be some sort of feet/meter conversion issue. The problem does just seems to be with ESRI Flex API as measurements have been correct everywhere else I've checked such as ArcMap and ArcGIS Online.

Anyone have any thoughts?

Re: ScaleBar showing wrong measure

BjornSvensson — Mon, 16 Apr 2012 20:15:24 GMT

We have a tiled basemap in wkid 3434 (NAD_1983_StatePlane_Arkansas_South_FIPS_0302_Feet)...

Is there a public service that we could test against?

Re: ScaleBar showing wrong measure

IvanBespalov — Tue, 17 Apr 2012 06:28:08 GMT

Bjorn,
we had same problem some times ago..

here is sample application (based on ESRI "Measure Line sample") with sources
Length measuring (draw tool + geometry service) != scale bar measured value.

Re: ScaleBar showing wrong measure

MattCharton — Tue, 17 Apr 2012 11:42:49 GMT

Is there a public service that we could test against?

Though it isn't secured, I don't think my client would appreciate me giving it out... I will PM it to you though.