We have self developed application based on ArcGIS 9.3.1 SP2. Our agents use that application to edit parcels. The parcel layer has a field
SHAPE_AREAthat is calculated by ArcGIS. Our application gets the value of the field property to show the area of the parcel. However we see now that the area is not always correct. The most flagrant difference we encountered was an area of 17ca (m²) instead of 29ca. I try to find out why the values are not correct and how many of those values are incorrect. To do that I open the
shapefilein ArcGIS 10.2.1. and I add a field named "area2" with the same properties as the field
SHAPE_AREA(type: double, number format: numeric, precision: 11, scale:4), I use
Calculate Geometryto get the area and i use the same projection. Then I add a field named "result" with the same properties. I calculate the field: SHAPE_AREA - area2 to get the differences.
Can anybody tell me why I get different results when both calculations are done by ArcGIS on fields with the same properties? And how we can resolve this problem?
The problem is with your self developped application. From your snapshot I can tell you are using a shapefile (it includes FID field and not OBJECTID); you also indicated in the body of your question. So the SHAPE_AREA field is created and populated by yourself.
Note that If you create a polygon inside a FileGeodatabase, Shape_AREA gets created (it is part of geodatabase functionality).
So to solve this situation, either use FileGeodatabase to store your featureclasses or post the sample code of the developed application in another question.