topic Transform a grid map into a contour map in Land Use / Land Cover / Forest Cover Mapping Questions

Transform a grid map into a contour map

GoldenJiang — Mon, 25 Jan 2016 00:28:10 GMT

I want to transform this grid map below (polygon, 10 m*10 m) into a contour map and make it less spotty. Is it possible to achieve so?

The value field only contains 10, 20, 30, which represent my management classes (calculated from excel spreadsheet).

Re: Transform a grid map into a smoothed contour map

DanPatterson_Retired — Mon, 25 Jan 2016 00:33:31 GMT

contour is for contours Contour—Help | ArcGIS for Desktop

but raster to polygon with Generalize option may work Raster to Polygon—Help | ArcGIS for Desktop

although I doubt you will be wholly pleased with the result given the coarse nature of the raster.

Re: Transform a grid map into a smoothed contour map

JayantaPoddar — Mon, 25 Jan 2016 06:07:45 GMT

You could try Focal Statistics (Spatial Analyst extension is required).

How Focal Statistics works—Help | ArcGIS for Desktop

Re: Transform a grid map into a smoothed contour map

DanPatterson_Retired — Mon, 25 Jan 2016 08:19:54 GMT

Jayanta... it won't help much with the chunkiness, that can slightly removed by converting to vector with generalize, then producing the raster at a finer grid cell size. then maybe focal stats to add in some edge randomization

Re: Transform a grid map into a smoothed contour map

NeilAyres — Mon, 25 Jan 2016 08:25:39 GMT

Use the cubic convolution renderer to smooth "blocky" rasters on-the-fly.

Re: Transform a grid map into a smoothed contour map

GoldenJiang — Mon, 25 Jan 2016 19:57:59 GMT

I have an idea: is it possible to generate points on the grid and then contour these points?

Re: Transform a grid map into a smoothed contour map

DanPatterson_Retired — Mon, 25 Jan 2016 21:47:13 GMT

of course... Point to Raster—Help | ArcGIS for Desktop

have you tried anything yet? You have several options now to test and compare

Re: Transform a grid map into a smoothed contour map

GoldenJiang — Tue, 26 Jan 2016 21:09:11 GMT

Hi Dan, the grid map I have is actually a polygon. I've tried 'polygon to raster' (cell size 1.3) and then 'raster to polygon'. Eventually I got this:

But it won't get rid of the spots...

Re: Transform a grid map into a smoothed contour map

SteveLynch — Tue, 26 Jan 2016 21:17:20 GMT

Golden

Please try Neil's suggestion and I'm sure that you'll get what you want.

By default we use nearest neighbor resampling when displaying a raster and you can change it to bilinear or cubic to get a smoother look.

-Steve

Re: Transform a grid map into a smoothed contour map

GoldenJiang — Tue, 26 Jan 2016 21:28:17 GMT

Can I remove the small spots on this to make the map tidier?

Re: Transform a grid map into a smoothed contour map

DanPatterson_Retired — Tue, 26 Jan 2016 21:36:39 GMT

Ok... confusion reigns... are you trying to interpolate a new surface given some input points etc or... are you stuck with what you have as an image/raster and you are trying to fix it up by smoothing it out?

Re: Transform a grid map into a smoothed contour map

GoldenJiang — Tue, 26 Jan 2016 21:50:27 GMT

My main purpose is to show more clear and practical treatment areas. I am sure I am getting closed: polygon to raster - create random points - extract values to points - kriging. I think it would get better result to create sampling points that are regularly distributed throughout the area, but I am not sure how......

Re: Transform a grid map into a smoothed contour map

DanPatterson_Retired — Tue, 26 Jan 2016 21:56:56 GMT

It has been suggested several times, that other interpolates will give you the smooth result that you appear to need. Do you have some comparative results so that any further suggestions might produce your desired result

Re: Transform a grid map into a smoothed contour map

DarrenWiens2 — Tue, 26 Jan 2016 23:02:36 GMT

See if this will work for you:

Original:

Point to Raster:

IDW: