Questions related to slope analysis.

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3
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1answer
258 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 ...
2
votes
1answer
83 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 ...
1
vote
1answer
31 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 ...
1
vote
1answer
78 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.
1
vote
1answer
54 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 ...
1
vote
1answer
44 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 ...
0
votes
1answer
66 views

Problem for slope map

I want o create one slope map for my model but I have one big problem. I have contours lines and mass points and I create a DEM using topo to raster but if I want to create a slope map from that DEM I ...
0
votes
1answer
39 views

How do you set sea level elevation to white in terrain analysis?

I have ASTER files I am working with to create a shaded relief background for some other vector shapefiles. In experimenting with different color-elevation options, I am unable to have the Terrain ...
3
votes
0answers
146 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 ...
3
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0answers
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 ...
2
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0answers
88 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). ...
2
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0answers
81 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 ...
2
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0answers
268 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 ...
1
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0answers
25 views

Performing Theil-Sen regression on raster data by R software

I have seven NDVI raster layers (in ERDAS img format) of an area. Each NDVI layer is the peak growing time of that year. I want to do trend analysis of NDVI values change over the years pixel by ...
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0answers
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 ...
1
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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- ...
1
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0answers
33 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 ...
1
vote
0answers
84 views

Split 3D line feature at vertices based on slope change

I've already asked a question about this subject, but now I think I'm almost getting to the point. I have to split roads in ramps to calculate LS factor (RUSLE - soil erosion) These are the steps ...
1
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0answers
341 views

validating the calculation of slope from DEM

my purpose is to calculate and validate slope in percentage of southern california using DEM and landsat data. step 1)i used a DEM file and changed with the float type file to integer type step 2) i ...
1
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0answers
195 views

cut/fill calculation tool to investigate if there is enough material to achieve a 30 degree slope

This is a cut/fill problem. We have pits that have been dug in the ground, usually rectangular. They have a bund wall around them. They are being rehabilitated by pushing the bund back into the pit. ...
1
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0answers
676 views

Calculating Accurate % Grade from GPS Coordinates

I am trying to calculate % Grade from GPS points. I am using the basic equation of (Rise/Run)×100 The problem is I am getting spikes in my GPS data (example 1 meter rise for 3 meter run), I am ...
0
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0answers
23 views

QGIS: calculate slope of line-segments

Using QGIS, I'd like to achieve the same as in question calculate-slope-of-street-segments. I have a shapefile with lines (rivers) and a DEM. So I suppose the best way is somehow like this: 1 - ...
0
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0answers
33 views

Problem with calculating slope in QGIS

Ive downloaded DEM form earthexplorer. But after calculating slope I only have blac img. with same value in min. and max. When calculating aspect or relief, DEM works correctly. Have you met with ...
0
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0answers
14 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, ...
0
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0answers
39 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: ...
0
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0answers
40 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 ...
0
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0answers
36 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 ...
0
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0answers
36 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.
0
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0answers
24 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 ...
0
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0answers
36 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 ...
0
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0answers
110 views

Issues creating slope raster layer from a point layer

I'm trying to create a slope raster layer using QGIS 2.0 on Windows XP. I started with a points layer with the Z elevation attribute. I then used the interpolation plugin to create a DEM. But, ...
0
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0answers
167 views

Estimating sunlight hours from slope, aspect, and latitude

I'd like to estimate annual sun hours (or insolation, or solar radiation) for 4 points, 1 each on the four sides of the summit of a hypothetical flat-sided mountain. I have slope and aspect for each ...
0
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0answers
349 views

Trying to build pyramids for large raster

I finally was able to make a slope with a rather large 5m DEM. But now I it usually wont finish drawing. When ArcMap asks to 'build pyramids' it always freezes sometimes instantly after accepting ...
0
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0answers
103 views

3D Polyline by Slope on Surface

I wish to project (continue/extend/whatever) a polyline upslope following a specified gradient along a DEM surface. Is there any way of doing this?
0
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0answers
225 views

How to calculate Gradient from DEM?

I have a digital elevation model for a catchment area and I would like to calculate the gradient by cells. Is that possible and does anybody know the steps?