topic Raster to Polygon, Fixing the Projection in Geoprocessing Questions

Raster to Polygon, Fixing the Projection

elizabethramirez — Tue, 31 Jan 2012 20:07:47 GMT

I have an ecosystem raster layer of the state of Florida that I need as a polygon shape file. The Raster file has 4 columns: Rowid, Value, Count and Class. When I convert it with "Raster to Polygon," there is no projection assigned, and half the state did not convert. Not realizing this, I continued working and dissolved the layer to similar rows as the Raster. Now realizing the problem with projection, I tried to project it using "Define Projection" and "Project" but neither worked. Both cases i imported the projection from another layer. The difference between the polygon and the raster are to the point where they lay next to each other and are different sizes.

I need help getting this layer to project correctly and to have the columns join with the raster.

Thanks

Re: Raster to Polygon, Fixing the Projection

MelitaKennedy — Tue, 31 Jan 2012 20:39:08 GMT

Does the raster have a defined coordinate system? If it doesn't, you should assign it the coordinate system that it's georeferenced to, not what you want it to be using the Define Projection Tool or the raster's property page in ArcCatalog. The polygon data should then inherit that information.

Melita

Re: Raster to Polygon, Fixing the Projection

elizabethramirez — Wed, 01 Feb 2012 00:30:47 GMT

Hi Melita

Thanks for your reply. The raster file does have a defined coordinate system (NAD_1983_HARN_Albers) but after the conversion, there was a message stating there wasn't any. The other concern is that when I imported the reference from another file, the other layers' defined coordinate system are different (NAD_1983_Stateplane_Florida_North_ FIPS_0903_Feet). I figured since they are line up, it should work, right? Not so much.

Liz

Re: Raster to Polygon, Fixing the Projection

elizabethramirez — Wed, 01 Feb 2012 01:04:28 GMT

It said, "the following data sources you added are missing spatial reference information. The data can be drawn in ArcMap, but cannot be projected."

Re: Raster to Polygon, Fixing the Projection

MelitaKennedy — Wed, 01 Feb 2012 20:40:06 GMT

Hi Liz,

That's interesting. Unless the original Albers definition is corrupt, it should convert fine. If you look at the raster's xy coordinate system in ArcCatalog, what parameters and linear units does it have? The converted polygon data should use the same coordinate system as the original raster. If the Albers definition is using meters, while the State Plane is in feet, that will definitely offset the values beyond the fact that it's also using Lambert conformal conic.

Melita