Hello,
I am working with discrete data instead of gridding. I need the area in degree^2 of polygons surrounds those data points.
In gridding process, we first assume that the grids are rectangular and the area equals to:
area1 = [ delta_latitude * delta_longitude]
Afterward, we multiply that value with cos(latitude) to give the actual curvature to the grid which is related to the actual position of the grid in the sphere;
area_final = area1 * cos(latitude)
I created Voronoi polygons for each data point with "Create Thiessen Polygons" function in ArcGIS and the function automatically gave me an "area" value for each polygon in the attribute table. I am wondering if those area values are already considered the curvature and the actual position of the polygons? Should I also multiply the area with cos(latitude)?
Thanks in advance,
Feyza
Don't do the math yourself, it will be wrong.
In a featureclass incarnation of the voronoi diagram or the delauney triangulation IF you left the units in decimal degrees, you might want to confirm the shape_area field with
Add Geometry Attributes... using the option...
AREA_GEODESIC | AREA_GEO: The geodesic area of the polygon. |