combining map data of similar dimension to produce new maps using algebraic operations

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1answer
19 views

R giving error when attempting map algebra

I'm trying to manipulate some downloaded rasters using R, and keep getting the same error when I try to do any type of map algebra. The example below uses a raster file downloaded from ...
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1answer
32 views

How to do loops on raster cells with python console in QGIS?

I'm new here and beginner with python. I'm looking for a solution to my problem for some hours but now you are my last chance... I'm using the python (2.7.5) console in QGIS (2.4.0). Is there a ...
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2answers
51 views

Nodata issues in map algebra

A dummy question. I need to change all values in my rasters into ones. I've been able to do this fine in the Rater Calculator just by multiplying the layer by zero and adding one (my_layer*0+1), but ...
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1answer
58 views

How to calculate cumulative sum conditionally across raster?

I don't know if this is possible without coding, but I need to: Create a raster file that, for each value in the input raster, sums all pixel values across the entire extent that are less than or ...
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1answer
92 views

How to compare two rasters and reclass the greater value(python script)?

I am working on an assignment that requires us to reclass a raster(via python) from two rasters. We need to compare the power received at one cell(on raster1) and compare it to the same cell on raster ...
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1answer
150 views

Raster Multiplication - Can't Multiply Sequence by Non-Int of Type “Float”

I am trying to multiply a list of GRID raster datasets using a different value for each raster. The value is in the raster name. Some examples are [wse_1979_5,wse_1980_0,wse_1980_5], where 1979_5, ...
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1answer
73 views

How to iterate RGB raster layers in ModelBuilder?

I have an RGB raster that I'm calculating color-based indices from. When I do the calculations manually, I can select a certain band of the RGB raster to calculate. I need to do the same operations on ...
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1answer
270 views

NameError: name 'Con' is not defined

I have 365 rasters with the same extent, and I am trying to sum them together by month. I have the script below, which was working until I added the line out1 = Con(IsNull(raster), 0, raster) which is ...
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0answers
27 views

Map algebra from QGIS python console? [duplicate]

What command do I use to do map algebra on rasters from the QGIS python console?
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1answer
375 views

Map Algebra - Grass GIS (r.mapcalc) merge two raster with NoData value

I have a slope raster and a road raster. The black pixels in the road raster are NoData values and the pink pixels have a value of 1. They don't cover exactly the same area. I want to create a new ...
2
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1answer
135 views

Efficiently check for equal adjacent values in raster calculator

I have a raster consisting of integer values in each cell. I want to check every adjacent cell in a 3x3 grid to see if any one of the adjacent cells has a value EQUAL to the center cell, and if so, ...
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1answer
136 views

Map algebra expression with dynamic raster layers

Attached is the model that i am working on. The "To Value" and "From Value" are model parameters and hence subject to change each time according to requirements, This leads to varying number of ...
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1answer
157 views

Raster produced by Con expression not saving

I cannot get a Con expression to work. Or, if it is working, I cannot get the raster produced by the Con expression to save. I have two rasters and I want the positive difference between the two, and ...
2
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1answer
218 views

Nearest Neighbor Focal Statistics and Map Algebra

I would like to use a nearest-neighbor type analysis to iterate over a raster. The nearest neighbor analysis will give a cell value of 1 IF AND ONLY IF the cell being analyzed has a cell value larger ...
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1answer
690 views

ModelBuilder: How2 pipe output of Iterate Raster tool into Raster Calculator tool?

Re: ArcGIS v10.1 ModelBuilder Hello, THE PROBLEM: Using ModelBuilder and map algebra, I want to compute a ten year average grid from a stack of 10. The problem is that only 1 grid (%raster%), the ...
5
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1answer
304 views

Error using con in Map Algebra in Python script

I am experiencing a painful problem in the middle of a Python script I am writing. When I get to a Map Algebra function, I have tried two different options and both return a different error. At first ...
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2answers
302 views

How to produce a mean raster file based on other raster files? [duplicate]

Possible Duplicate: Tools to flatten the jp2 to a single band (average the bands)? I have a number of raster files from a same area, that coordinates of corresponding pixels perfectly match ...
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0answers
133 views

Map Algebra in VB.NET Add-In Tool

I'm trying to run a map algebra expression in a vb.net add-in, and can't seem to get it to work. It's a roving window that interpolates noData areas in a DEM. The expression works in the Python ...
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2answers
2k views

Using individual bands from a multi-band image in ArcGIS 10 raster calculator

I'm trying to use individual bands from a multi-band TM image (IMG file) within the raster calculator in ArcGIS 10 (SP2/3). I can add individual bands to my MXD, but raster calculator will only use ...
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0answers
188 views

How can I ignore NoData values in map algebra? [duplicate]

I need a way to exclude NoData from calculations. I don't want any NoData cells from any of the rasters to be used in pick or con statements.
2
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1answer
480 views

Spatial Analyst tool Look up but in ArcView3.2

Is there any option how to do a Spatial Analyst tool "Look up" operation from ArcGIS 10 in ArcView 3.2? I have a grid with attributes and need to "extract" values from the table field (values from ...
9
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3answers
611 views

Creating raster by randomly choosing cell value from multiple overlapping rasters?

I'm using ArcGIS Desktop 10 with its Spatial Analyst extension. How do I combine multiple rasters into one, always choosing randomly from the values of overlapping cells? I have an image that may ...
3
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1answer
407 views

Change raster value for an area based on a class of another raster

I would like to change all raster values in raster A that fall into the locations of category/class 1 of raster B. Here, some more details. I did a calculation on a DEM resulting in different ...
4
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2answers
2k views

For Loop - Map Algebra (ArcGIS) using Python

ORIGINAL QUESTION Im relatively new to python and these fourms but Im am having trouble utilizing for-loops for spatial analyses within ArcGIS. It does not appear to recognize the variable, ...
4
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4answers
598 views

Compressing map algebra outputs from ArcPy

When creating a raster map algebra output, is it possible to set its compression? I'm creating a model which generates many hundreds of rasters, and currently each is being stored without any ...
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1answer
837 views

Partially updating raster (DEM)?

How to update an .img DEM in ArcView 9.3? I do have DEM which need to be updated only if few parts. The area to be updated has been produced in separate DEM with Spline Interpolation with Barriers. ...
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4answers
299 views

What are some Domain Specific Languages (DSLs) for GIS?

I'm curious what sort of domain specific languages (DSLs) are used in GIS. The only one I can think of is the DOCELL language that was provided in ArcInfo Workstation GRID, but is no longer ...
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8answers
2k views

What raster-based GIS systems really work?

Raster GISes like GRASS, ArcGIS/Spatial Analyst, and Idrisi can perform a rich set of data processing and analytical procedures loosely known as "map algebra." In today's computing environment it is ...