area in degree2 by voronoi

FeyzaSakil — Tue, 17 Apr 2018 14:07:55 GMT

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

Re: area in degree2 by voronoi

DanPatterson_Retired — Tue, 17 Apr 2018 19:23:39 GMT

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.

topic area in degree2 by voronoi in Spatial Data Science Questions

area in degree2 by voronoi

Re: area in degree2 by voronoi