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Questions tagged [slope]

Use this tag when asking questions related to slope analysis.

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17 views

Incorrect slope values for points in QGIS [duplicate]

I'm trying to determine the slope of sampling points in QGIS 3.4, but the values are all ~89.99°, which I know is incorrect. Pretty sure it's an issue when creating the slope raster. Based on the ...
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29 views

Create a land-use raster in which the “crop cells” are distributed in dependency on the slope?

I have a geo-"scientifical" question. If you don’t know the answer, but have a hint how to search for the solution, this information would be helpful as well! In Germany we do not get land-use data ...
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1answer
25 views

Seeing heights in Landsat 8

I have downloaded some DEM from Landsat 8 from usgs website. when I opened the compressed file I saw some Tiff files and two text files. I opened the txt file using ArcGIS 10.7 and it contains many ...
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1answer
17 views

Slope and side-slope of vineyard rows

I have a question about interpreting the slope and side-slope of vineyard rows using a line vector layer and a DEM. I am trying to calculate the slope along the row (split into 2 meter lengths) as ...
2
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1answer
44 views

Obtaining slope and aspect for points in QGIS

I'm new to QGIS. I have GPS points uploaded to QGIS and a ⅓ arc-second DEM (USGS) of the area. I'd like to generate slope and aspect data for each point. What is the best way to do this? The ...
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1answer
40 views

Technical documentation for GDAL Slope

I was running a gdal slope calculation on DEM I had gdaldem slope B:/data.tif G:/slope.tif -of GTiff -b 1 -s 1.0 and I need to find the concert documentation on how the slope is calculated. https://...
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13 views

Analyzing Sonoma County's topography/slope in 2017 fires

I am looking to create a map of sonoma county's topography. I am looking at one of the components of a fire: slope. I want to first isolate sonoma county, which is easy enough to do, after that ...
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3answers
84 views

Using QGIS polygonize tool to create discreet slope polygons

I am trying to create a shapefile with polygons representing areas of different slopes. I am running into some problems using the following workflow. I start with a digital elevation model and using ...
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0answers
45 views

Correcting slope of river bed on DEM using QGIS or ArcGIS

I have a DEM that has incorrect value of altitude/slope in the river bed area. This is a result of the interpolation of elevation value that are close to the river and creates lots of errors. In fact ...
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22 views

Reclassify slope raster

I want to reclassify a slope raster as part of Least Cost Path Analysis, but I'm a little bit confused about the reclass rules. My rules look like this at the moment (numbers left are degree): 0 ...
6
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1answer
365 views

Average Cross Slope Calculation

My county ( Pima, Arizona ) uses a number called “average cross slope” which they define as ACS = (I * L)/A where I = contour interval L = length of contour lines in the area A = area ...
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39 views

Slope and Aspect calculations giving wildly different results based on zoom using Leaflet

I asked Accessing slope and aspect data using Leaflet? last week about getting slope and aspect as a function of lat and lng in leaflet, and I am in the process of trying to code out a good answer. ...
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53 views

Accessing slope and aspect data using Leaflet?

I am building an application in leaflet, and I need to be able to access slope and aspect as a function of latitude and longitude. Currently I am able to get elevation data from the mapbox elevation ...
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0answers
45 views

QGIS Slope analysis thinks elevation unit is degrees making all slopes 90 degrees or 0 degrees [closed]

When i run my slope analysis the output has only two values: 0 and close to 90 degrees. The only way I have found to solve this is using a z factor of 1/111,120 which is the conversion of degrees to ...
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1answer
37 views

How do I view and export table with slope data for raster and TIN?

Using an original point file, I created a DEM raster with IDW interpolation as well as a TIN. I used surface analysis to create 3D slope layers, one with degrees for the raster (IDW) and one with ...
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1answer
40 views

Comparing Slope among various DEM resolutions?

I'm comparing the slope products derived from DEMs of various spatial resolutions (1m, 10m, 30m) for a set area. The trend I find is that as the resolution improves, the areal extent of various ...
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0answers
23 views

Correcting forestry acreages due to slope to get actual acreages treated [duplicate]

I came up with a process to get actual acreages vs map acres of steep slopes, but I am wondering what others do to correct for steep slopes and get actual acreage treated? For mine, In ArcGIS Desktop, ...
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1answer
67 views

Calculating average slope using ArcGIS Pro?

I want to rate for ease of walkability for one track, I have a road shapefile and raster of the slope. Any ideas about how to calculate average slope or other methods to do that?
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1answer
53 views

Which layer for least cost analysis?

I'm new to least cost analysis. I have a DEM-layer of a region and I want to know what's the least cost path from a to b. Do I have to use the DEM layer to calculate that? I also have a hillshade ...
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2answers
105 views

Labeling DEM or slope layer with slope angle in degrees?

I have a shapefile and made a DEM raster to create contours and slope analyze puttinggreen for a golf area . I have all i need except the slope values in degree (labeled directly in the map along with ...
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1answer
160 views

Digital Terrain Analysis - Roughness Index [closed]

Currently I am working on a project dealing with terrain analysis based on a DEM. I came across the term "roughness index" using slope values from that specific DEM. On YouTube I found a video, which ...
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0answers
43 views

Calculating variable buffers using slope between river and point 100' away using ArcGIS Pro?

I have a network of streams that I need to buffer based on a basic rule set. This buffer will depend on the slope. The slope is determined by the looking at the difference in elevation between a ...
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0answers
64 views

Extract longest flow path in ArcGIS pro

I did calculate Hydrology with Spatial Analysis tools==> Hydrology and now, I have streams and Watershed. In each watershed, I need to extract the longest Flow as a polyline for calculate slope. What ...
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58 views

Python error on QGIS

We are doing the slope analysis for one of our clients and can find the following error every time we do the analysis. We have not faced this situation in the past. The QGIS version which are using is ...
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1answer
191 views

GRASS GIS producing different slope than GDAL?

When producing a slope in GRASS GIS 7.4 the results are different than with QGIS (GDAL) and ArcMap for the same input data and same parameter (Z ratio is 1.0 and degrees). QGIS and ArcMap generate ...
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24 views

Selecting Certain Slope Class That Is Not Surrounded Narrowly By Other Class

not sure how to brake it down, but let me try i've created a slope classification with this class now what i'm looking for is how can i select the class of 0%-8% that is not surrounded narrowly by ...
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2answers
125 views

Adding slope values to attribute table (QGIS 3)

I have a DEM raster and some points (one .shp for all points) plotted on it. I would like to know if there is a way to add the slope value of the pixel that each point is located in the attribute ...
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1answer
122 views

Using QGIS 3.2 to add slope and/or % grade to county-wide street layer?

Using QGIS 3.2 what is the best way to add slope and/or % grade to a county-wide street layer using the following data: Streets (polylines) = 35k records (10mb) Contours (polylines) = 500k records (...
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60 views

Extracting slope of aspect information using QGIS?

In What is SOA (slope of aspect)? @Spacedman explained to me what SOA means. Now I need help to understand how I could work with it and extract the data that I want. I want to use Qgis (with Grass ...
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1answer
54 views

What is SOA (slope of aspect)?

I’m reading an article that the authors talk about extracting values of SOA (slope of aspect). I can’t find anything related to that on Google. This article reference is : ZHOU, Yi et al. Automatic ...
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1answer
103 views

Finding glider reachable area / catchment area with custom slope?

I'd like to produce maps for gliders in mountains. I'm looking to display the reachable area by a glider taking off from a given point (obviously with the corresponding DEM). For a first approach I'...
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1answer
68 views

Identifying flat-ish hilltops in a DEM?

I am working on a project where I need to identify the area of a hilltop that is relatively flat within which stone structures could be built before the slope becomes too great to build without having ...
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1answer
90 views

Seeking CSMapMaker (QGIS Plugin) equivalent for ArcGIS Desktop?

I'm looking for a tool or script or set of operations to mimic the output from a certain QGIS plugin called CSMapMaker, wherein curvature, slope, and a gaussian filtered DEM are overlain one another ...
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41 views

Performing raster analysis using Arcpy - in_memory does not preserve raster shape

I am creating a script tool using Arcpy and it transforms elevation data into a final clip polygon as part of a lengthy site selection tool. When I perform the raster analysis and save my intermediate ...
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1answer
37 views

Slope is not consistent with the elevation of DEM and seems to be incorrect

I have a DEM image which shows the elevation is from approx. 81 to 103. I expected the slope should be 0-22m. However, the result from DEM-Terrain Model-Slope is from 2.5 to 13.2. Anyone knows why?
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87 views

GdalDEM slope error in Jupyter

I try to calculate slope data. This is the DEM source https://www.earthenv.org/DEM Firstly, I translate data with gdal.Warp according to image UTM zone. Original image .bil extension so first I ...
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1answer
67 views

Estimating slope by fitting a quadratic surface (Evans 1980) in ArcGIS Pro

I am needing to calculate slope using the quadratic surface method of Evans (An integrated system of terrain analysis and slope mapping, 1980), but not sure how to implement it in ArcGIS Pro. A GRASS ...
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1answer
277 views

LS Factor in SAGA (slope units)

In which units do I have to calculate Slope to use as an input for the LS Factor tool in SAGA (degrees, %, radians)? I couldn't find anything in the documentation.
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1answer
107 views

Strange output from QGIS Raster Terrain Analysis plugin

This is closely related to several other questions on this site: here, here, here etc. However, my issue is not resolved by following the answers provided. I am using the Raster Terrain Analysis ...
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0answers
74 views

Calculating maximum extent of debris flow from point with mean slope value

At a very large scale I perform a spatial analysis for which I have to apply mean slope criteria. These criteria allow me to calculate the maximum extent of an event (debris flow). I know that below a ...
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1answer
260 views

How should I interpret R terrain/slope output in degrees?

I'm calculating the average land gradient (in degrees) in Brazil and I do not know how to interpret the results. As I'm calculating the slope in degrees, 0.25 is 0.25 degrees, 25 degrees or should I ...
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1answer
45 views

Creating slope map with ArcGIS Desktop?

I created slope map with DEM model in ArcGIS Desktop. But it is only categorize in to two sections. I think it is problem with the horizontal and vertical scale. I used WGS84 coordinate system. How ...
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0answers
16 views

Calculate average slope values for a point using 50ft vector perpendicular to contour

I am trying to calculate the average percent slope of a hillside on either site of a data point. I tried extracting info from a DEM using a radius around the point, but I believe a more accurate ...
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1answer
175 views

Statistics of slope in individual polygons (asset) on Google Earth Engine

I have a single shapefile with multiple polygons, uploaded to GEE as an asset. I am trying to find the mean slope (using SRTM elevation imagery) in each of the polygons, on GEE. However, I get only ...
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0answers
61 views

Slope rasters - different results from different tools

I'm calculating Least Cost Path (LCP) within QGIS 2.18. The first step is to produce the slope raster from the DEM. Using r.slope in GRASS produces excellent results where I can go on and finally ...
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1answer
47 views

Convert slope file to calculate the percentage of the coverage

I calculated the Slope of the area that I'm working on, and I was wondering if there is a way to calculate the actual percentage of each bracket, meaning the percentage of contribution of each class. ...
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1answer
93 views

Converting RTK Elevation Data to DEM?

I have a shapefile that contains elevation data. I want to eventually convert this to a slope layer. I'm assuming I have to convert to a raster, then a DEM, then slope. Is that correct? If so, ...
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0answers
22 views

QGIS/GRASS: forecast slope variation in slope by a new road

For preliminary project purposes, I wonder if there is a way to forecast and calculate with QGIS and/or GRASS the variation of slope dued by new road, starting with terrain DEM and a project sketch of ...
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1answer
87 views

What the default unit in QGIS 2.18 $area is calculated and etc?

I'm a beginner in QGIS . We are using 2.18 version. What are the basic units for area and slope, etc? SI, so means m, m^2, °? Or I can set it by myself? If it's possible to set it, where?
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1answer
614 views

Creating polygons of specific slope percentage from a slope raster in QGIS

I am trying to extract all areas where the slope is greater than 20% and then turn those areas into a polygon. I'm using QGIS 3.0.2.