All Questions
30 questions
1
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0
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231
views
Make a slope-aspect map and create a circular legend for it in QGIS
I'm working on Terrain analysis of my ROI and could compute aspect and slope separately. Although I found a fairly easy tutorial on how to make a slope-aspect raster, I want to know if it's possible ...
- 11
0
votes
1
answer
49
views
Combine Slope and Aspect of a DEM for suitiable PV-Powerplants
I want to get areas for PV-Powerplants via QGIS.
I used the solution under Filter for south pointing areas from a DEM for extraction of the areas which are not facing north (60-300°).
But I need ...
- 745
2
votes
0
answers
97
views
Distort buffer on slope direction in QGIS [closed]
I'm an archaeologist and an average QGIS user, not advanced at all.
I'm studying a method for the mountain archaeological contexts. My aim is to define some influence areas around the sites and ...
- 21
1
vote
0
answers
207
views
How to calculate exact slope and aspect for a polygon
I want to calculate the aspect and slope for polygons, because they appear as fruit-growing areas.
I got the DEM 1m for my datas and calculated aspect and slope with the QGIS functions. Then I ...
- 11
0
votes
1
answer
209
views
Correct measure unity for slope and aspect in order to work in QGIS with "r.sun.insoltime"
I'm using QGIS 3.10 and I should create a raster that shows the hours of sunlight referring to a given day for my province. r.sun.insoltime (Fig. 1, sorry it's in Italian but I traslate) to work asks ...
- 23
2
votes
0
answers
244
views
Correct format for slope and aspect in order to work in QGIS with "r.sun.insoltime" [closed]
I'm using QGIS 3.10 and I should create a raster that shows the hours of sunlight referring to a given day for my province. r.sun.insoltime (Fig. 1, sorry it's in Italian but I traslate) to work asks ...
- 23
1
vote
0
answers
32
views
Using WCS DEM data for make slope and aspect maps in QGIS [duplicate]
I need to do several slope and aspect analyses (hundreds).
Instead of downloading an ASCII for each location, I want to extract/clip the elevation data from wcs and do the analysis.
This is the WCS ...
- 41
1
vote
1
answer
62
views
Define point locations in relation to slope [closed]
I have a dataset of settlements that I would like to put in relation with slope and aspect layers that I have made to see if there is a preferred altitude or direction (facing north or south, etc.) ...
- 89
0
votes
0
answers
52
views
How to find all cells within a neighborhood with slopes towards the center?
I would like to iteratively go through each cell in a raster in arcGIS that meets criteria (already established as per below description) and find the percentage of cells in a several km neighborhood ...
- 1
2
votes
1
answer
220
views
QGIS Raster Mask Layer?
I have a raster slope layer and a raster aspect layer. The slope layer is single band grey, that is black to white, with white as the steepest slope. The aspect layer is pseudo colour.
I'd like to ...
- 163
1
vote
1
answer
100
views
Identifying slopes surrounding a lake (in ArcGIS)
I'm working with ArcGIS 10.7 to investigate lakes in the mountains. I have created a 2km "hazard buffer" around every lake-TIN showing instable slopes (>40°) above the lake surface from where a ...
- 759
4
votes
1
answer
1k
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 ...
- 305
2
votes
0
answers
221
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. ...
- 500
3
votes
1
answer
635
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 ...
- 500
0
votes
0
answers
218
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 ...
- 691
1
vote
1
answer
163
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 ...
- 691
0
votes
0
answers
75
views
Why is my aspect not displaying the full data?
I am trying to get the slope aspect for the altitude shown above. Can someone please advise me on why this may not be working properly?
0
votes
1
answer
557
views
Selecting a subset of a raster, based on aspect and slope, as input to calculate area
Background
I created some digital elevation models and subsequently made a 2 layer raster for each containing the calculated aspect and slope using raster::terrain. Now I want to calculate the area of ...
- 59
4
votes
1
answer
2k
views
Conditional Statement (CASE-WHEN) in QGIS for slope aspect
After processing a DEM with a mask to get the aspect values of some polygons I would like to create a new field classifying those values as N, NE, E, SE, S, SW, W, NW.
I've written this but I can't ...
- 333
4
votes
0
answers
2k
views
Calculating slope and aspect from DTM lidar elevation data in ArcGIS Desktop? [closed]
I have an ASCII 2m lidar DTM file which I converted into a raster in ArcGIS with the From ASCII to Raster tool. From this DTM file I would like to calculate the slope and aspect. I have used the ...
- 49
1
vote
1
answer
384
views
Calculating an "overarching" slope and aspect for each polygon of a feature class
I have a feature class containing polygons and an associated raster with elevation data. I'm looking to calculate a single slope and aspect for each polygon within the feature class. I don't want a ...
- 13
1
vote
1
answer
3k
views
Selecting south-facing slopes with slope > 10° using ArcGIS Desktop?
I have to make a Model in the Model Builder which will select the areas with slope bigger than 10° and which are facing to the south. It should be used for environmentalist who will just insert a DEM ...
- 373
0
votes
1
answer
2k
views
ENVI files (datafile +hdrfile) not displaying properly in python
I am trying to topographically correct my already atmospherically and radiometrically corrected images. To do so I need to calculate illumination conditions at the time of image acquisition. Terms in ...
- 304
1
vote
1
answer
2k
views
Methods in Slope, Aspect SAGA calculations
Using this algorithm in QGIS I can choose between 7 methods, the default one being by Zevenbergen & Thorne 1987. What's the difference between them and can I just use the default one without ...
- 229
0
votes
1
answer
661
views
Cleaning up a raster
I recently completed a project that involved slope, aspect, and solar radiation to find optimal rooftop locations for solar panel installations. For my final map I combined the rasters that showed the ...
- 193
3
votes
0
answers
273
views
Extracting cells from raster by attribute in ERDAS Imagine
I have a raster file that gives me the slope of all the hills and mountains in an area in degrees (0-90) and I need to extract all the cells which are >= 45 with an operator in the model builder. I ...
- 113
8
votes
1
answer
4k
views
Rotating symbols per attribute value in QGIS?
I am trying to apply a rule to rotate symbols based on the value of an attribute.
I tried to copy Automatically changing the angle of a symbol in QGIS?, which is essentially my question, however it ...
- 848
3
votes
1
answer
275
views
Information about algorithm used by Terrain models
I have calculated slope and aspect using the DEM (Terrain models) GUI in QGIS Essen. I was also able to calculate the profile and tangential curvature using the toolbox r.slope.aspect. I was wondering ...
- 53
0
votes
1
answer
1k
views
Merging slope angle and aspect rasters
I have created slope and aspect from a DEM layer, I reclassed both slope and aspect into categories (for example slope is now a value of 1-6) and turned them into polygon layers where each polygon has ...
- 27
4
votes
1
answer
983
views
Using 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 ...
- 43