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Questions tagged [analysis]

The process of extracting geographic, statistical, geometric, or scientific information from one or more related collections of GIS features and data.

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Network Analyst takes so long

Is there some kind of limitations of number of features when we work with Network Analyst in SDE ? My net has 170.000 features, is it a problem ? Because it take at least 6 hours to finish the "Build ...
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25 views

QGIS DEM files do not behave the same way using the Viewshed Analysis plugin

Software and platform: QGIS 2.18.20 Windows 10 pro My issue is as follow: I am doing a Viewshed Analysis of a single site, where multiple DEM files (*.img if it makes a difference) are needed. I ...
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1answer
17 views

How to define the angle of points on slope?

I have point data set and DEM and my task is to identify how many points are falling on the slope of more than 40 degrees. How could I do this in ArcMap?
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40 views

Using the height of river to approximate its extreme flood boundaries - terrain analysis in QGIS?

Using QGIS I'm trying to analyse an area/DEM with this criteria: - heights 10 meter above the river-centerline in both sides of river. I can do it with the calculation of contours (2m) from DEM and ...
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21 views

Performing GPS data analysis on Android Location?

I am currently writing an application for android and am saving the users location to an database. The data consists of: Lat/Long Timestamp in millis Accuracy (estimated horizontal accuracy of this ...
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1answer
109 views

Calculating population size from raster layer using QGIS?

Is it possible (using QGIS) to calculate the population size from a raster layer within a certain area? For example: I have a population density raster layer (100x100 grid cell) for South Africa, ...
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1answer
70 views

Make rasters to show the extent of certain data values

I'm trying make a raster of the area between 5 and 10 thousand feet in Colorado. I have DEMs, and I'd like to make a raster where all the area in this range is a value of 1, and the area outside the ...
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51 views

how to create center-lines from amorphous-shaped polygons [closed]

I would like to create road-center lines for amorphous-shaped images as in the example. void area is shown with white and solid area is shown with black. So I would like to create a center-line for ...
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17 views

How to calculate mean coordiantes, using two conditions with QGIS? [duplicate]

I am currently working with OSM data, using QGIS 2.18. Actually I am wondering how to reduce the number of displayed points "public transport stop_positions". Is there a way to calculate mean ...
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0answers
101 views

How to solve Python error for raster analysis interpolation nearest neighbor in QGIS [closed]

I am trying to interpolate temperature values into a raster using QGIS 2.18.15 in Windows. I need the output file as a GeoTIFF (.tif) file. I have my input for temperature already in a shapefile, but ...
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1answer
19 views

Private Surface Water Mains In Between Public Mains Analysis

I am working in a geometric network of a surface water (stormwater) system. We have both public and private assets (pipes/mains, manholes, inlets/CB's, etc.) in the network. I am doing a bit of QC on ...
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126 views

Standard Method to calculate Average Moving Speed from Times & Coords?

...I wasn't sure if this question was best suited to GIS, SO or Math, so after reading GIS Topics I decided to ask here, but I'll relocate if necessary... :-) I'm working on automating various ...
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183 views

how to calculate cumulative cost of movement, accounting for wind direction, in R?

I am trying to reproduce the calculation of the duration of sail-powered navigation as described in an academic article (http://www.tandfonline.com/doi/full/10.1080/15230406.2017.1403376), but using R ...
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1answer
131 views

GWR with dependent and explanatory variables in different files

I have a point shapefile (let's say A) with pollution measures (let's say Y). My hypothesis is that pollution at theses locations is primarily driven by nearby industrial units and not by activities ...
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0answers
34 views

Road Network Accessibility

I am working in qgis with 3 layers: one is road network and other is hospitals and locations of accidents , later two layers are as points, I want to figure out what accident location (points ) are ...
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25 views

no vector analyses tools in qgis 2.18.7, how to get the tools like pointcount etc? [duplicate]

I am using QGIS 2.18.7 and in recent history i used all kinds of vector anaysing tools. Now i have some polygon vector data and point vector data and i really don't understand why i don't see the ...
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2answers
155 views

Determining if polygon falls within another polygon using QGIS?

How can I determine if a certain polygon falls within another separate polygon using QGIS?
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1answer
37 views

network analysis that includes user defined nodes

I want to make network analysis using python. I want that user must be able to select point of interests and calculated route must contain that points. For example between start and end nodes user, ...
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18 views

Are tesselation patterns an effective way of covering a shape?

I am using Facebook place search to explore business pages on Facebook. If I input a longitude and latitude into facebook's GraphAPI, I can search within a given radius for facebook business pages. ...
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0answers
19 views

Cutting a line by a list of varied percentages along [closed]

Does anyone know a way to cut a line at specified percentages along that line? I know you can do this in ArcGIS if you have a specific percentage in mind, but I want to do it at varied percentages (5, ...
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1answer
70 views

Why does my RAM cap out around 150 MB when doing the Distance Matrix analysis in QGIS?

I am currently trying to determine the 2 nearest points for a database of 8 million people against 425 locations. I have 2 csv files uploaded into QGIS one with a unique number for 8 million people ...
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132 views

QGIS temperature analysis

I have the thermal orthophoto of photovoltaic plant and I want to find out "max" and "min" values of temperature in the specific area on the module (the temperature is an attribute for each pixel in ...
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45 views

Slope Analysis from Raster and Contour Lines do not match QGIS [duplicate]

Having run the slope analysis using Terrain Analysis with a percentage output, I found that my outputs ranged from 0 to 0.013, with virtually all land ranging from a slope of 0 to 0.00326. Measuring ...
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2answers
591 views

Moving GPS points with distance + bearing [closed]

I have a list of 73 GPS points that represent animal observations. Each point also lists the bearing (angle in degrees) and distance from the observer to the animal. Instead of displaying each point ...
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1answer
126 views

solar potential analysis of 3d city model [closed]

I am looking for a free application/tool/plug-in to conduct solar potential/irradiation analysis on a 3D city model. My intention is to know how much solar energy is delivered onto the rooftops and ...
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0answers
75 views

Is it possible to combine buffer zone analysis with time series analysis in QGIS?

There is a multitemporal analyzer in QGIS where it is possible to do a buffer zone analysis combined with time series analysis, where there are two layers an input layer and a target layer and the ...
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1answer
695 views

Classifying slope (flat, slope, steep, very steep) in QGIS? [duplicate]

I want to classify the slope of the DEM data, by dividing the slope by 4 classes: flat, ramps, steep, very steep. How to do this with QGIS?
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1answer
211 views

Using QGIS to find and calculate parts of polylines within polygon?

I've already got QGIS (2.18.2) to add an ArcGIS shapefile with polylines create a polygon which is a buffer region around a subset of the polylines in the ArcGIS file add a KML file with one polyline ...
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1answer
276 views

QGIS Calculating Line Lengths and Statistics

I am working through this tutorial: http://www.qgistutorials.com/en/docs/calculating_line_lengths.html In the tutorial we import a shapefile map of railroads,clip the data through a selection/...
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1answer
61 views

How to devise the time to cross a raster's cell knowing the speed of movement?

Let's assume I have a raster representing the speed of movement in Km/h, and the raster cell size is, say, 500m. Am I correct in understanding that, in order for me to calculate the time it takes to ...
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1answer
514 views

Shadow impact of building on certain area [duplicate]

I have done some research but was not able to find a solution to my task! What do I want: Pretty simple - I have a building and I want to know how its shadow is influencing a certain site at ...
4
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1answer
365 views

Algorithm or GDAL module to calculate LOS

I'm involved in a project using GDAL via python. We need to be able to calculate if, standing at point A it is possible to see point B, given a DEM. To clarify we do not need a viewshed algoritm, we ...
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2answers
225 views

Analyse points within buffer

Quite new to using GIS and have a (probably very simple) question. I want to see if there is a greater occurrence of a species around a certain feature. i.e. is there a greater density of a species ...
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82 views

How to do regression analysis in SAGA for topographic correction

Currently I am trying to do the topographic correction using C-Correction. I would like to know if there is a way to do the regression analysis between L (uncorrected reflectance of each band from ...
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2answers
456 views

Rose diagram of direction values of polyline vector layer

I have a vector layer of polylines with a set of multiple lines having length and bearing (azimuth in plane). I need to make some statistics on these lines, including the construction of rose diagrams ...
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0answers
74 views

How can I analyse the visibility of the urban area in ArcMap? [closed]

I want to analyse the visibility of the urban area using ArcMap. I saw the image below and I want to have the same output. Can you explain the process and steps to obtain this output?
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1answer
324 views

ArcGIS Combine Fuzzy Membership and Weighted Sum

I would like to combine the workflow of fuzzy membership and weighted overlay for a suitability analysis and would like to ask if this is "allowed" scientifically. I have severeal criteria, some ...
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1answer
127 views

Tutorial for raster analyse in ArcGIS or QGIS [duplicate]

Does anybody know where I can find some good tutorial for raster analyse in ArcGIS or QGIS?
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298 views

How to delineate a zone of slope break

I have a DEM of a region and want to delineate about a half-mile region at the base of hills (e.g. an area where the slope changes from steep to shallow). I ran the slope analysis tool and it kinda ...
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1answer
62 views

Temporal analysis in GIS - Tool to identify the jump points

I'm searching for a tool that help to analysis spatial temporal data in GIS. This is my problem: I have a database with a set of 170 georeferenced ovitraps (traps to catch mosquitoes eggs) with the ...
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2answers
231 views

Proportional Coloring within polygon for multiple variables

I'm new to QGIS and I am doing some demographic analysis of Ethiopia. I have a vector map with each of the country's administrative zones: Within the attribute table, I have data for religious ...
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23 views

Analyze if a pop is adequately served/distance to amenity

This may be more of a conceptual than technical question. My question is how to best analyze if a population is adequately served by an amenity, say, supermarkets. If I assume that for non-urban ...
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133 views

Is there a tool that is similar to Detect Feature Changes but for points?

We recently had data collected by multiple companies. The data is similar but we're finding discrepancies. Knowing this, we need to analyze all of the data. I'm hoping to find something similar to ...
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67 views

Kernel Density - Retail Analysis

I am wondering if anyone can provide feedback on how to conduct a density "kernel" analysis (example below)? I have two files: POINT SHP file with SIZE (sm) data (SHOPPING MALL) POLYGON SHP file ...
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2answers
477 views

Limit radius of ST_Clusterwithin (PostGIS)

I have a set of over 800k points and I am looking to cluster them within specified circle radius. I need them to be clustered to maximise the number of points within the circle. This is to model how ...
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1answer
55 views

What Algorithms to use for Levee breach Analysis?

I have a (relatively) High resolution DSM of the Country side, and want to figure out the extent of area that will be flooded if the Embankment/levee fails at a a given point. Something like this: ...
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1answer
327 views

Road Graph in QGIS

I am learning transport related analysis in QGIS. While using Road Graph (Shortest Path), after giving the specifications, the shortest path panel is not being displayed. Could some one help?
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1answer
141 views

Calculate % of point features within a certain distance/buffer

I am relatively new to ArcGIS. I have point data of specific locations (e.g. doctor’s surgeries). I have buffer rings around these points of 0.5 miles (roughly 10 mins walking). I want to calculate ...
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100 views

GRASS 7.3 r.fill.dir Does Not Create Output Raster

I am running GRASS 7.3 on Mac OS X El Capitan (2.9GHz, 8GB RAM). I have had to disable SIP in order to run it, but it works. I am hoping to perform some hydrological analyses on a few DEMs. My DEMs ...
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0answers
33 views

Working with intersecting polar grids

I'm having some trouble figuring out the best way handle some GIS data. I want to analyze pollution from specific sites at specific points. I have a list of sites I'm interested in all across the ...