eDraw widget - incorrect area calculations?

[EricVenden]

I'm guessing it's my config file - possibly, but the eDraw widget is not calculating areas properly.  Linear distances are fine, regardless of the units chosen, but perimeter and area calcs are not.  I double-checked the area units and conversions and they are correct.  I have also checked that my Geometry service was "good" and that the spatial reference was correct.

I have downloaded a clean copy of the widget and it still behaves the same.

I have also used the Draw widget and it DOES properly calculate perimeters/areas.

Any ideas?
Thanks for your time.
Eric V
Gurnee, IL

[RobertScheitlin__GISP]

Eric,

   So the most likely issue is that you have set your spatialref to some non meter base WKID

<spatialref>102003</spatialref>

102003 is web mercator and uses meters so is good if you changed yours to some state plane that uses feet than the calculations will be off.

[EricVenden]

Too easy. Thanks Robert

[ArgoonChuang]

Hi Robert,

I happened to see this old thread. First of all wkid 102003 is "USA_Contiguous_Albers_Equal_Area_Conic" instead of web mecator, which shall be 102100. I am not aiming to correct you but just a long hanging question when using your enhanced draw widget: Is this gonna making any difference on the calculated result ?
 
Thank you,
Argoon
 
http://help.arcgis.com/en/arcgisserver/10.0/apis/rest/index.html?pcs.html
 
102003 - USA_Contiguous_Albers_Equal_Area_Conic
PROJCS["USA_Contiguous_Albers_Equal_Area_Conic",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Albers"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-96.0],PARAMETER["Standard_Parallel_1",29.5],PARAMETER["Standard_Parallel_2",45.5],PARAMETER["Latitude_Of_Origin",37.5],UNIT["Meter",1.0]]

102100 - WGS_1984_Web_Mercator_Auxiliary_Sphere PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator_Auxiliary_Sphere"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],PARAMETER["Auxiliary_Sphere_Type",0.0],UNIT["Meter",1.0]]

[RobertScheitlin__GISP]

Argoon,

   True, the main thing is that you choose a WKID that is as specific to your locale as possible that uses Meters as the map units althoughUSA_Contiguous_Albers_Equal_Area_Conic will provide a good measurement for area it will be less accurate with lengths. so you have to have some knowledge of Spatial references and the trade off of equal area and equal distance projections. I find that a UTM projection for your zone will work the best for most people.

[GeorgeHaskett]

Robert,

I know this is an old thread, but I thought it would be better to add to this then create a new one.

I'm search for some clarification.

I have a web map that covers both Idaho and Montana.  It appears that the default setting for the spatialref is 102003.

I changed my pointunits to include the following:

102668 - NAD83 State Plane Idaho East
102669 - NAD83 State Plane Idaho Central
102670 - NAD83 State Plane Idaho West
102700 - NAD83 State Plane Montana
4326 - WGS84

Will these settings work okay or should I try to find something closer to the two states instead of 102003?
If so, do you have any suggestions?

Would using one of the options above instead of 102003 help or just skew the measurements?

Thanks,

George

[RonaldWisner]

I have a slightly different problem. My calculations, line and area lengths, are correct in the display but when the user double-clicks to add the measurement label it is very different from the diaplay.

I have no idea what would cause that. Any ideas?

Thanks,
Ron

[RobertScheitlin__GISP]

Ron,

   There is not really enough info in your post to come up with a guess on. But is sounds like an issue from an older version of this widget. What version of the widget and viewer are you talking about?