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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1answer
29 views

Is there any chance that I can find shapefiles of buildings in Qingdao, China? [closed]

We are starting a new esearch project in China and I've been looking for a while and the closest thing I can find is buildings of Beijing. But I need Qingdao not Beijing. It seems like I will have to ...
0
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1answer
40 views

Analysing landuse data in a buffer layer

In my project I want to analyse the landuse around some points within a certain radius. So I created a buffer around my points but I have no idea how QGIS could probably tell me what different ...
2
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0answers
439 views

Performing Raster Algebra and Multicriteria Analysis using FME?

I'm trying to use FME to do some raster algebra for some Multi-Criteria Analysis. At the moment, I have three rasters, all with the same extents and resolution: Slope, Hydro, and Infrastructure Mask. ...
18
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1answer
497 views

What GIS analysis techniques were used in determining Gale Crater as the landing site for the Curiosity Rover?

What specific GIS analysis was used in determining Gale Crater as the landing site for the Curiosity Rover? I'm assuming factors such as slope, elevation, ruggedness, etc were used as well as ...
8
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4answers
2k views

How to represent bimodal attribute value distributions on a map

I'm looking for a visualisation method that enables me to represent bimodal or even multimodal attribute value distributions on line features. A bimodal distribution has two different modes that ...
3
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1answer
41 views

Assign points within 150 meter buffer of each other the same unique identifier?

I have a bunch of points on a QGIS map. Each point is a unique sampling event. However, some of these points have been sampled multiple times but there is no common identifier in the attribute data to ...
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0answers
28 views

Vector to grid - Computing statistics by grid cells

I have a vector point data from drifting buoys (speed, direction, sst, slp) that I want to analyse in a grid. What are the right tools for this? Example of my points data below. Each point has the ...
2
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1answer
61 views

Do Not Filter vs Ignore Invalid Geometries

In QGIS 3, What's the difference between "Do not filter (better performance)" and "Ignore invalid geometries"? Both can be found at Settings > Options > Processing > General Both are options to ...
0
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1answer
37 views

Viewshed Analysis for Custom DEM file [closed]

I am new to qgis and trying to do 2 things. My objective is to have an accurate viewshed analysis at the end. But my DEM file is of poor resolution. I do have a shapefile with building height ...
2
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0answers
44 views

How to automatically compare two aerial photographs with a GIS with regard to certain features?

At present, we are trying to automatically record the new use of land by buildings by systematically comparing aerial photographs (e.g. 2007 farmland -> 2008 warehouse). For this purpose, high-...
4
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0answers
247 views

How to estimate the average width of a sidewalk? [duplicate]

I have a table with two polygons representing urban block with and without the sidewalk: geomBlock and geomBlockWithSidewalk. On my city we can approximate the polygons of geomBlockWithSidewalk to a ...
7
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3answers
844 views

How to get a list of adjacent lots to a road in ArcMAP and PostGIS/QGIS?

In the following map, I have: A line / road layer A parcel / lot layer The Task: Find and count the list of lots adjacent to the road with their types (parcel_type is a field in the parcel layer) ...
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1answer
511 views

Using ArcGIS 10 to find areas of overlapping use and areas with low use?

I have a spatial data set that shows areas of use (several different types of use) on the landscape. I am looking for ways to overlay these spatial use layers so that I can show where the areas of ...
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1answer
28 views

Selecting Different points in 2 different layers

I'd like to make an analysis on points. I've 2 layers they have house numbers as an attribute. What i'd like to do is compare these 2 layers and select the different ones. Geometrically there are ...
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1answer
198 views

Network service area - QGIS

I want to check if schools from my hometown are accessible for students who use public transportation, so I need to perform this analysis in order to see if the schools are located in the range of ~...
1
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1answer
136 views

Stereoscopic Interpretation on QGIS [closed]

I would like to know if anyone has worked with stereoscopic analysis (e.g extracting features such as drainage, forest an so on) using the following softwares: QGis, gvSIG, ILWIS or MicroImages TN ...
1
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1answer
110 views

Count points in polygon (weighted) for multiple attributes in QGIS 3 in one go

Is there a way to count weighted points inside polygons for multiple attributes at one time? I can count weight points (below) for an individual attribute, which creates a new polygon layer with an ...
2
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1answer
261 views

Count points in polygon (weighted) in QGIS 3

In QGIS 2 you could perform a weighted point within a polygon layer using Processing toolbox > Vector Analysis > Count points in polygon (weighted). I could well be missing something, but I can'...
46
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5answers
11k views

What are the benefits of hexagonal sampling polygons?

I am always on the lookout for useful methods to sample or partition study areas (usually in the form of raster datasets) into smaller units. Recently, I read an ESRI blog post about a new tool for ...
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0answers
40 views

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 ...
0
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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?
5
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0answers
63 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 ...
0
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1answer
356 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
74 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 ...
1
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1answer
252 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 ...
2
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1answer
157 views

Identifying nodes in GRASS?

I am running a Salesman analysis and get the following error message: Terminal at node [1860] cannot be connected to terminal at node [1923] I have been able to identify one of the nodes by a ...
3
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2answers
630 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 ...
2
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0answers
148 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
22 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 ...
2
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1answer
192 views

How to aggregate values multiple from multiple points along a route as an attribute of it?

I have a route network with a "Name" field that identify every route. On the other hand I have a shapefile of points. Each point corresponds to the number of people using a route at a time t. I would ...
3
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2answers
1k views

Volume of Land Below Sea Level

How could one use a GIS (or other appropriate system) to calculate the change in mean ocean levels across the world if all the land below sea level were flooded (Death Valley, Caspian Depression, Afar ...
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0answers
315 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 ...
5
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2answers
9k views

How to perform a slope analysis in QGIS? [duplicate]

I have contour information in the form of line features (see picture below) and I want to do a slope analysis in QGIS. Is it possible?
2
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0answers
324 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
208 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
48 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 ...
2
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1answer
65 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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1answer
146 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?
3
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2answers
402 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 ...
2
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1answer
274 views

Joining points in multiple polygon features? Union with points and polygons?

I have a shapefile full of points (points.shp) and another shapefile with polygons (polygons.shp). Polygons.shp has multiple features in it, many of them overlapping with each other. I would like the ...
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2answers
438 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?
2
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1answer
5k views

Compute mean coordinates

Can anybody explain how to compute mean coordinates?
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0answers
22 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. ...
-1
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1answer
173 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 ...
1
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0answers
79 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 ...
1
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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, ...
3
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1answer
71 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 ...
2
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2answers
203 views

Spatial analysis? Two layers?

One is LandPlot and the other is Soils. When I open the LandPlot attribute table I see I have 500 specific plots of land. When I open the Soils attribute table I see I have 5 types of soils (let's ...
2
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2answers
925 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 ...
9
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2answers
10k views

Creating noise maps using ArcGIS for Desktop or Open Source Desktop GIS? [closed]

In a previous role I helped create Noise Maps for Northern England. The predicted noise levels was done using the IMMI package (which I can recommend) and the cartographic output was done in ArcMap. ...