[GIS] Eliminate 0 Values From Raster

arcgis-10.2arcgis-desktoparcmappolygonraster

Arcgis 10.2

I currently have a raster file that I want to turn into a set of polygons. This will help me to create specific buffers around certain points. The extent of my values are 0, and 1. When I change from raster into polygon, I end up with polygons for both 0 AND 1. I only want polygons for pixels with value 1. If I have polygons for values of 0, I end up capturing a bunch of empty space that it totally not necessary to the project.

Here is an image of what I am working on (white = 1, black = 0):

enter image description here

Best Answer

you can use raster calculator to set your 0 values to NoData. Con(condition, value if true, value if false) will set the false value to Nodata if it is left blank.

in your case, you could use

Con(raster== 1, 1)

a more generic code would be

Con(raster!=0, raster)

when you convert to polygon, NoData pixels will be ignored.

Note that you can make something equivalent to the vector buffer using "expand" on your raster.

Related Solutions

[GIS] Plot a Raster in R with white space for NA values

It seems like the band you are plotting does not have the NA values correctly specified, and has a value of 94 instead, otherwise its hard to explain how you get the above plot result. So you have to clean that data layer.

One option to do that could be to make an overlay with another band from the same raster. If you have another layer otherband with correctly specified NA values with the same "structure" as r (i.e. the NA values in another band are the same as in the one you show above), you could overlay those two.

rna <- overlay(r, otherband, fun=function(x,y){if(is.na(y)) return(NA) else return(x)})

If you want to try the conversion instead, I would suggest reclassification. The raster package has a memory efficient function for reclassification of rasters. Your could replace the value 94 with a NA value with the reclassify function.

rna <- reclassify(r, cbind(94, NA))

[GIS] Displaying raster Background Value as hollow for more than one set of RGB values using ArcMap

Since 10.1, you can use the image analysis tools (Windows > image analysis) to create a mask function that will perform the masking on the fly

Using the Mask function, you will specify one or more NoData values or a range of valid pixel values.

The inputs for this function are the following:

Input Raster / NoData Interpretation / NoData Values / Included Ranges

NoData Interpretation refers to how the NoData values will impact the output image.

All—The NoData values you specify for each band must occur in the same cell for the output image to contain the NoData cell.

Any—If the NoData value you specify occurs for a cell in a specified band, then that cell in the output image will be NoData.

Here are the paraphrased instructions on how to implement this, from ESRI's documentation:

Adding a function

Each function in a function chain is represented by a function symbol function. To begin adding functions for the first time you need to click the Add Function button on the Image Analysis window. If the raster layer contains a Functions tab you can modify the chain and functions within that tab. If you wish to generate a new raster layer in the table of contents with an edited function chain, click the Function Editor... Add Function button. Getting to the function chain can vary, depending on if it exists.

These steps describe how to add a function to a raster layer for the first time.

In ArcMap, open the Image Analysis window (click Window > Image Analysis).

Select the layer in the Image Analysis window and click the Add Function button. The Raster Function Editor window opens containing a default function chain. The Identity function exists when there is no other function. Once you add a function, the Identity function disappears as it is no longer necessary.

Right-click the Identity function, click Insert, then click the Mask Function to add. When you add a function, it is inserted above the function you clicked.

Modify its settings and click OK. Once you click OK, the function chain will be validated. If the function you are adding invalidates the function chain it will not be added. You cannot drag and drop functions to change their position within the chain. You need to remove a function and add it to a new location if you want to move a function.

Best Answer

Related Solutions

[GIS] Plot a Raster in R with white space for NA values

[GIS] Displaying raster Background Value as hollow for more than one set of RGB values using ArcMap

Adding a function

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