Questions related to slope analysis.

learn more… | top users | synonyms

1
vote
0answers
37 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 ...
0
votes
1answer
68 views

Determine start/end points for line slope calculation [duplicate]

This is a follow up question based off of this question. I have a line feature class representing storm drains and a point feature class representing where storm drains are connected. The point ...
0
votes
0answers
36 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 - ...
1
vote
1answer
60 views

Calculate slope of line based off of point layer

I have a line feature class that needs to have its slope included as a field. I have a point layer that contains points and their elevations for the start and end of the line segments. How can I ...
2
votes
1answer
36 views

Calculating slope for points with downhill slopes rendered as negatives in ArcGIS

I have a DEM and a series of points. I'd like to measure the change in slope along the series of points. Distinguishing between uphill and downhill slopes matter to me, and ArcGIS' slope function ...
0
votes
0answers
35 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 ...
1
vote
1answer
35 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 ...
0
votes
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, ...
1
vote
1answer
37 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 ...
0
votes
0answers
43 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
votes
0answers
41 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 ...
1
vote
1answer
49 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 ...
4
votes
1answer
98 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 ...
1
vote
2answers
169 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 ...
0
votes
0answers
42 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
votes
0answers
37 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.
1
vote
0answers
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 ...
2
votes
2answers
147 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 ...
0
votes
0answers
25 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 ...
3
votes
1answer
292 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
votes
1answer
72 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 ...
1
vote
2answers
87 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 ...
2
votes
1answer
113 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 ...
1
vote
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
vote
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 ...
4
votes
3answers
109 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 ...
1
vote
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
vote
1answer
83 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
votes
1answer
158 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 ...
3
votes
1answer
167 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 ...
3
votes
2answers
278 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 ...
2
votes
1answer
135 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?
2
votes
0answers
89 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). ...
3
votes
0answers
151 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 ...
0
votes
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 ...
1
vote
1answer
56 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 ...
0
votes
0answers
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
votes
1answer
86 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
votes
0answers
82 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
votes
1answer
55 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 ...
1
vote
1answer
501 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
votes
2answers
159 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
votes
1answer
54 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 ...
1
vote
2answers
241 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
votes
1answer
291 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 ...
0
votes
1answer
387 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, ...
1
vote
1answer
542 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 ...
1
vote
0answers
36 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
votes
1answer
109 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), ...
3
votes
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 ...