topic Re: sum the area of all pixel classes in Data Management Questions

sum the area of all pixel classes

sadiajame — Thu, 12 Apr 2018 15:49:55 GMT

I have a map with three different types of pixels 1,2 and 3 and these are for three different area counts. 1 corresponds to less than 607 pixels, 2 indicates 607 to 10,000 pixels, and 3 indicates > 10,000 pixels. 607 pixel is 15 acres and so class 2 and 3 would be more than 15 acres. I need to know how can I sum the area of all pixel classes?

Can zonal statistics would be helpful?

Please help!

Re: sum the area of all pixel classes

DarrenWiens2 — Thu, 12 Apr 2018 17:19:28 GMT

If your raster is integer data type, you can open the attribute table and see the pixel count for each class. Otherwise, one of these tools should get you there:

Zonal Statistics as Table—Help | ArcGIS for Desktop

Tabulate Area—Help | ArcGIS for Desktop

Re: sum the area of all pixel classes

sadiajame — Thu, 12 Apr 2018 21:07:30 GMT

Thank you for your time. But I have to create a map which is showing the area as acres as I have three categories. Can you help me with that?

Re: sum the area of all pixel classes

DarrenWiens2 — Thu, 12 Apr 2018 21:34:03 GMT

I guess I don't understand the problem. If you know the number of pixels in each class, and you know the size of the pixel, then you can figure out the area of each class. But, perhaps that's not what you're after.

Re: sum the area of all pixel classes

DanPatterson_Retired — Thu, 12 Apr 2018 21:37:44 GMT

If it is a raster layer that you have, are you trying to convert it to a polygon layer?

The chances of getting that exact area back are minimal, so you really need to show what you have and why you need those exact values. Is it for an assignment?

Re: sum the area of all pixel classes

sadiajame — Fri, 13 Apr 2018 13:41:41 GMT

Thank you for your input. Let me ask me question another time. I have 4 drainage raster dataset for the four states such as IA, WI, IN and MS. Raster files contain three categories of pixel (pixels 1,2 and 3 and these are for three different area counts. 1 corresponds to less than 607 pixels, 2 indicates 607 to 10,000 pixels, and 3 indicates > 10,000 pixels. 607 pixel is 15 acres and so class 2 and 3 would be more than 15 acres) and cell size of each raster is 10m. Yes, I have to create a 5 minute dataset that provides the area of the grid cell suitable for drainage, by summing the area in classes 1, 2 and 3. Then I have to create a fraction of grid cell map by dividing the sum by the grid cell area.

Can you please suggest me something on that.

-Thank you!

Re: sum the area of all pixel classes

sadiajame — Fri, 13 Apr 2018 13:43:57 GMT

Let me clarify the question another time. I have 4 drainage raster dataset for the four states such as IA, WI, IN and MS. As you know they contain three categories of pixel (pixels 1,2 and 3 and these are for three different area counts. 1 corresponds to less than 607 pixels, 2 indicates 607 to 10,000 pixels, and 3 indicates > 10,000 pixels. 607 pixel is 15 acres and so class 2 and 3 would be more than 15 acres) and cell size of each raster is 10m. I have to create a 5 minute dataset that provides the area of the grid cell suitable for drainage, by summing the area in classes 1, 2 and 3. Then I have to create a fraction of grid cell map by dividing the sum by the grid cell area.

-Thank you!

Re: sum the area of all pixel classes

ChadKopplin — Fri, 13 Apr 2018 14:18:19 GMT

Take your count field squared * 0.0002471054 (if your cell size is in meters) or 0.000022956 (if your cell size is in feet) in order to get your acres. First add an acres field to make this calculation in, then just sum the acres field.

Re: sum the area of all pixel classes

sadiajame — Fri, 13 Apr 2018 15:26:05 GMT

Just to make sure one thing that, the cell size is 10 m. Is that I need to take the count field* 100 sq.m *0.0002471054 ?

Re: sum the area of all pixel classes

ChadKopplin — Thu, 26 Apr 2018 18:41:56 GMT

That is correct.