Questions related to slope analysis.

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1answer
25 views

Mean watershed slope - are there better methods than taking the mean of the contained slopes?

I am wondering if there are better methods for determining the mean watershed slope, other than taking the mean of the slope values contained within the watershed? For example, could or should one ...
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12 views

Another Z-Factor Challenge

I've been working on a DEM, trying to calculate the slope. I have it in WGS_1984 and re-projected into NAD_1983_MTM_8, my preferred projection for this project. Every time I run the slope tool, ...
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1answer
27 views

How to perform slope using PostGIS?

I want to perfom Slope using PostGIS. I used this query but i got a strange result unit : create table my_slope as SELECT ST_Slope(rast,1,'32BF','PERCENT',1, false) as slope FROM my_raster I wonder ...
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34 views

Problem in running r.slope.aspect in GRASS

I am new to GRASS GIS, and have been trying to use the r.slope.aspect function to find out the slope, dx and dy rater map from an elevation map(512*512)[1]. But I am getting the following output: ...
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33 views

How to make a map showing the slopes of the terrain

I am not too familiar with techniques, and was looking for ways to make a slope map for a given area. It ended with finding this site and posting the question. We are in the process of zoning a new ...
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1answer
37 views

Why slope tiff image produced with QGIS does not show properly in paint?

So I have this slope tiff image that I created using a DEM reprojected in meters. When I view it in QGIS, it shows fine. If I try to edit the picture in paint or Gimp afterwards, I dont see the same ...
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1answer
85 views

How to use SRTM Global DEM for Aspect calculation?

I need to derive a raster representing aspect for North America (from STRM data, originally in geographic lat/long). In most projections, true north is only map north along eg the central meridian so ...
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2answers
125 views

How to properly get the slope from an ASTER DEM in QGIS?

I have inserter a raster dem layer from ASTER satellite and I want to get a raster that has the slope of the area. I use terrain analysis > slope but the output is so wrong. Why is that? here is the ...
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27 views

Calculating a proper slopemap using GDAL

I have a DEM GeoTiff where I already calculated a hillshading and it looks perfect. Now I'd like to create a slopemap so that I can mark parts of a mountain that are very steep. The problem is that ...
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35 views

How to calculate curvature for a 3 D polyline (Z) in arcgis 10 with 3D analyst?

I'd like to add curvature calculations to 3D polylines (with multiple vertices) that have elevation for each vertex. I know average slope can be calculated using the Add Z information tool.
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37 views

How do I make a constant slope elevation model in arcMap? [duplicate]

I am currently working with ArcMap to develop an elevation model of a quarry showing how the terrain at the quarry site would look post-closure. One of the requirements is that the slopes placed along ...
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2answers
126 views

What is the “best” way to automate the GIS slope and aspect algorithm?

I am currently obtaining slope and aspect of roofs using ArcGIS as follows: Mosaic several Lidar .asc files to new raster Extract by mask using Mastermap building outlines to get hold of just the ...
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21 views

edit tif from dem by polygon selected in arcmap

i need to edit the tif of dem generated from agisoft photoscan using the arcmap to do a slope map from area. how to select the pixels and change their altimetry information mainly in trees locations ...
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1answer
229 views

How to compute average slope and area-weighted average slope?

I am learning GIS for use in hydrologic analysis. Related to computation of overland flow there are two types of slope that I would like to be able to obtain from GIS. The first is average slope for ...
4
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1answer
64 views

Calculation of surface derivatives at the edge of the raster

I was wondering how does ArcMap10.2 calculate surface derivatives (slope, aspect) at the edge of the raster, since the Horn algorithm is used and uses the 8 neighboring pixels around each pixel. When ...
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2answers
78 views

Range of values in slope and aspect changes when I try to unproject my projected rasters

I use the SRTM DEM and I have used the "Project Rater" tool in ArcGIS10.2 in order to project it from GCS_WGS_84 to a certain UTM zone in WGS84. With my projected elevation raster, I have calculated ...
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1answer
91 views

SRTM DEM with 16 bit signed pixel type changes to 32 bit float when creating slope/aspect/curvature

I have mosaiced 8 SRTM DEM tiles in order to get one raster layer of elevation. When I use "Mosaic to New Raster" tool I set as a pixel type format "16 bit signed" because this is the format that SRTM ...
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20 views

Creating a new surface for a track layout with defined gradient of slope

I am trying to establish a way of creating a new raster surface for a new track layout. I have a section of track, and I have a DTM. I want to give my track section a height value and a width. However ...
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0answers
17 views

Calculating Slope, Flow Accumulation and Topographic Wetness Index (TWI) using ArcGIS for Desktop? [duplicate]

I am working on a project that requires me to extract values from rasters (viz the slope and TWI) for a set of point dataset that I have. I tried calculating the Slope, Flow accumulation and the TWI ...
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3answers
86 views

How to resample a 30m DEM to a 100m slope raster properly?

I need to resample a 30m DEM to a 100m slope raster. Do I just resample the 30m DEM directly to the 100m slope raster? or, do I convert the 30m DEM to a 100m DEM and then create a 100m slope raster ...
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0answers
39 views

Connect two contour line with calculated line lenght

Is it possible to make plugin for qgis like PEGGER for arcview 3.2? Problem is, how to make path over contour lines with a grade in percent Formula is: K= e*100/G*M ; K=10*100/0.08*10000=1.25m K- ...
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1answer
76 views

How to display steep slopes with the use of Contours?

I am using Arc Map 10.1. I have downloaded contour data as a shapefile. Is there any way to use the contours to display steep slopes so 15%-25% or 25% and greater.
4
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1answer
138 views

Identifying south facing mountain land, above an elevation, within a slope range, less than fixed distance from major roadways

This odd question comes from believing that such an analysis is plausible in a GIS system. Only, I don't how to accomplish the various discrete steps implied from the Title, nor where to get a topo ...
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1answer
153 views

How to subtract out the slope (in general) of a DEM?

I'm searching for a solution process to subtract out the slope of a DEM like this: I have a high resolution DEM and want to reconstruct historical/old/not active parts of a river. The problem is ...
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2answers
210 views

Querying slope data using raster calculator: why are all results true?

I am using ArcGIS 10.2.2. From a DEM, I have created a new raster showing slope using the slope tool. The color scheme was automatically classified into 9 tiers. What I want to do is query this raster ...
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1answer
107 views

QGIS has an automatic way of finding the LS factor?

I wonder if is possible to calculate LS (soil erosion) factor automatically in QGIS? Or at least a way to calculate the length slope?
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0answers
84 views

Finding the slope of a polyline in QGIS 2.2 Valmiera

I am trying to find the average slope of a water course. I've drawn in the water course as a polyline over a large number of contour lines (the water course is long with a very large catchment area). ...
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0answers
136 views

How to display the slopes that only facing west using ArcGIS for Desktop?

Here is what I am struggling with ... In ArcGIS for Desktop I have to Derive and symbolise areas considered susceptible to avalanche risk based on the following simple rules: areas with a slope ...
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0answers
34 views

saga:slopeaspect curvature

I'm using windows 7 on 64 bit and using Qgis 2.6.0.I'm trying to process some Tifs from the console using the processing toolbox and saga:slopeaspectcurvature. This is pretty much how my code looks ...
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1answer
51 views

Seeking finer points of slope statistics within set of polygons?

Do not mark as duplicate please.. I have a few questions related to finding slope statistics (min, max, mean, standard deviation) of slopes (1-meter LiDAR DEM derived) within a set of polygons ...
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24 views

Looking to fine the average slope within a polygon [duplicate]

Question not a duplicate.. please help; I am using ArcGIS 10.2 (not open source software) and I have a high resolution DEM, 1.0m resolution, and I am looking to find the average slope and range of ...
2
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1answer
79 views

Calculate regional slope from DEM

I need to calculate regional slope for a coastline using a ~500 meter DEM covering a coastal plain and continental shelf where the slope for each grid cell is calculated by defining elevation extremes ...
2
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0answers
78 views

How to calculate the slope with isolines/raster?

I'm trying to calculate the slope (in %) in ArcGis 9.3, but don't remember how it works. I already did it some time ago, but this time it doesn't work... I used a shapefile with Isolines (see ...
3
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1answer
53 views

ArcPy Slope Script - Trouble Saving

I have an ArcPy script that applies the slope function to raster files in ArcGIS. I tried running the script with two raster files in the table of contents, and the script runs, but only saves one ...
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1answer
417 views

How to calculate the river slope for a lot of rivers automatically in ArcMap?

I'm working with ArcMap 10.2 and I'm pretty new in this area.. What I want to do is compute the river slope for a lot of rivers from a DTM...I know that there is a way to do it manually passing by ...
2
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2answers
147 views

Arcpy Slope Analysis Script

I'm trying to run slope analysis in ArcGIS. I have written an ArcPy script that converted feature layers to raster files. Now I have a list of rasters (each with a unique name) in the table of ...
4
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1answer
52 views

How do I consider entity alignment against slope direction?

I am a newbie to QGIS and don't know if the following is possible so would be grateful of any thoughts. I have a hill, most of which is given over to rectangular pasture fields. I hypothesize that ...
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2answers
229 views

Calculate area inside polygons based on slope

I have some DEMs and have computed the slope in degrees for each one. I have also classified the slope raster into the following 5 classes: 0-3, 3-15, 15-35, 35-50, >50. What I want to do is to ...
2
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1answer
245 views

Error when slope creating using ASTER 30m DEM

I have tried to create a slope map using ASTER 30m DEM obtained from internet. But when I use it to create (using ArcGIS 10 & 3D Analyst) a slope raster, the output is only 0-89 range. My ...
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1answer
320 views

Determining the slope of a DEM (SRTM-data) in QGIS

I'm new to QGIS and I have to calculate the slope of a DEM (I use srtm-data). I already detected the geoalgorithms toolbox and I also produced a raster layer with the slope using the tool "slope, ...
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1answer
422 views

How to create the attribute table for a raster that was produced by the Slope Tool (ArcGIS10)?

I use the Slope Tool (Spatial Analyst Tool – Surface) of ArcGIS10 by ASTER GDEM (that was exported to UTM projection). The program produce new raster (with slope value), but the resulting raster ...
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0answers
29 views

gdaldem slope attribute passing

How to pass slope attribute to the command "gdaldem slope manj.tif outpiu.tif -p use percent 45 -s 111120/370400" It's giving error like FAILURE: Too many command options. give any ...
2
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1answer
100 views

How to disassociate roughness from slope

How to measure topographic roughness irrespective of slope in ArcGIS? I have used many methods to generate roughness layers, including TRI, VRM (which is supposed to be less correlated with slope), ...
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26 views

How to re-slope a given DEM to pre-determined slope in ArcGIS?

I have a set of topographic contours of a mine and like to re-slope those areas alongside the river to a pre-determined slope, say 22˚; and 27˚ for water pond wall. The existing slopes along the river ...
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1answer
43 views

GRASS: v.drape, v.split and v.to.db on spearfish sample data

I am new to GRASS and started training on the spearfish sample data set in GRASS 6.4.3. I selected a bicycle tour and transformed it into a polyline. My next goal is to read out the slope and ...
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3answers
2k views

Creating a Slope Map Using Contours

I am trying to create a slope map. I have many contour elevation files. I tried to use the slope tool in Arctoolbox, but it calls for raster files and I'm working with vector data. Any help with this ...
2
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0answers
248 views

In ArcMap, when using Add Surface Information, why are all avg_slope values positive?

I've got a polyline shapefile and a LIDAR elevation dataset. I've successfully used Add Surface Information (from 3D Analyst) to calculate the average slope (avg_slope) of each line segment. The ...
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2answers
74 views

Compare slopes between adjoining line segments

Using a DEM, I assigned slope values to individual segments in a street network feature class. In some areas the slope values seem suspect, such as where a highway overpasses a local road. Is there a ...
1
vote
1answer
256 views

QGIS Slope Classification Issues

I am very new to QGIS for the primary purpose of creating a slopes layer so we know where slopes are above 15% or 20% or whatever we finally decide. I have used our DEM to create a slope geotif and ...
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3answers
1k views

Calculating slope in percentage

I'm working with qgis, v. 2.0.1. I have several soil types. They are (amongst others) described with slope indications. I already calculated the slope from the dtm in degrees, but as de description of ...