Calculating Area of Polygon

Hi, I am trying to calculate the area of each grid point in a polygon data set. I have latitude and longitude arrays which are 224X1 and 240X1 respectively. How do I go about writing code to determine the area covered in each grid cell when the resolution is 1/8th of a degree? I am a beginner to matlab so any and all help is appreciated!

Answer 1

[Image Analyst]

Did you know about the polyarea() function, and try to use it?

[Stephanie Goldstein]

I neither knew about the polyarea() function nor used it. What I know is that the area should be calculated by ((2*pi*R)/360)^2)*cos(theta)*delta_latitude*delta*longitude but I have no idea how to translate this into matlab code. Does this make sense? Thanks for responding.

[Image Analyst]

Translate your latitude longitudes into regular linear numbers (not degrees, etc.) then set up x and y coordinates at the vertices of the polygon you want (rectangle, triangle, or whatever), then pass into polyarea(). I believe it assumes that the polygon is 2D, flat, not bowed like on the surface of the earth. Do you have the mapping toolbox? Maybe there is some function in there to do that?

[Stephanie Goldstein]

Hmmm I do have the mapping toolbox. I'll see if there is a function which would allow me to do that. Sorry, when I say I'm a beginner I mean I'm really a beginner. What would be the purpose of translating the latitude longitudes into regular linear numbers? Also, any hint as to how I might do this?