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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159 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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36 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 ...
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1answer
202 views

Weighted polygon-feature-classes combination/overlay analysis using ArcGIS for Desktop?

I have several (sometimes, not always overlapping) Polygon Feature Classes which are all weighted/ranked through a field from 1 to 10 (10 is best). I would like to combine/overlay these layers them, ...
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1answer
67 views

Can I split my data based on the polygons in a different layer?

Carto has a built-in dataset with polygon data for UK administrative regions. I have put another layer over this, containing several thousand data points (postcodes). Is there an easy way to find out ...
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1answer
57 views

Calculating standing times

I have n objects and each object has m positions. Every position is defined by x, y (in millimeters) and a (unix) timestamp. { objId: 'a-b-c', x: 123, y: 567, date: 123456789, } Now I want ...
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45 views

Analysis of concentrations

I process images of trace gases concentrations distribution over the layer of atmosphere. I need to analyse values of concentrations, rather detect so-called "background" values and "extremal" ones ...
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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?
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1answer
195 views

How to group overlapping polygon features to generate unique feature ID?

I have a group on onshore leases that are overlapping and I want to generate a field attribute so that all the polygons (or centroids of the polygons) that overlap have a unique ID so that I can ...
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2answers
192 views

How to calculate shortest distance from start to end of river?

How can I calculate the straight distance from the start to the end point of a river (red line in image)? I don't know how to do this automatically.
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1answer
51 views

Add a random value of the order of 10^-2 to raster layer?

I was doing some raster analysis for smoothing in ArcGIS, one of my task is adding a random value of the order of 10^-2 to a raster layer. Does anybody know how to do it?
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2answers
369 views

Do any Basketball Coaches use GIS?

The LA Times has a leaflet map viewer app showing all 30,699 shots in Kobe Bryant's career. It seems like spatial analysis could be useful for certain coaching decisions. Are any coaches actually ...
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1answer
67 views

Cell-by-cell analysis of values of buildings in a city

I'm absolute new in GIS. My task is to estimate the wind energy potential in a part of a certain european city by using a given method which is based on the calculated roughness of cells of one ...
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2answers
449 views

QGIS NDVI Spatial Analysis

I have an NDVI raster that I would like to reclassify into some arbitrary bins i.e. all values between 0 - 0.2, 0.2 - 0.4 etc. for spatial analysis. Could anyone advise how to: 1) reclassify a ...
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1answer
568 views

Nearest Neighbour analysis between points in 2 tables utilizing with distances set along specific polyline roads

I'm trying to do a Nearest Neighbor analysis between points in 2 tables utilizing with distances set along specific polyline road files I have. I am attempting to determine the most cost effective way ...
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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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1answer
37 views

Is there any water quality toollbox which can be used in water quality analysis [closed]

I just start my job in water quality analysis,I wonder that do we have any toolbox to do water quality analysis in GIS
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1answer
80 views

The source of and possible solutions for DEM anomalies?

I am working with a DSM (Digital Surface Model) created using stereo-paired spot 6/7 satellite imagery. This DSM, and metrics derived from it will be used to create a Predictive Ecosystem Map (PEM). ...
3
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1answer
195 views

Distance matrix tool, how to include distances at 0 metres?

I have used the Vector -> Analysis Tools -> Distance matrix to merge two datasets by the closest points. But in my output csv file, the points that match exactly, or that has 0 metres between them ...
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1answer
83 views

QGIS: Distance Matrix tool omitting some points in output table. (qGIS 2.10.1-Pisa)

I have used the Analysis Tools -> Distance matrix to merge two datasets by the closest points. But in my output csv file, some of my points are left out. In the original datasets, none of these points ...
3
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1answer
514 views

Counting polygons in one layer that are overlapping/touching/contained in each polygon in separate layer of contiguous polygons using QGIS?

I have a layer of contiguous (pink) polygons (UK Parliamentary constitutencies) and a separate layer containing (blue) polygons representing protected nature areas (Natura 2000 areas): Each ...
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2answers
193 views

How to set independent path in QgsOverlayAnalyzer >> intersection statement using Python?

How to set independent path in QgsOverlayAnalyzer >> intersection statement using Python? QgsOverlayAnalyzer.intersection(QgsVectorLayer, QgsVectorLayer, QString, bool onlySelectedFeatures=False, ...
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1answer
62 views

Does ArcGIS Online include High Speed Rail in its network analysis?

I'd like to run an OD Matrix using network analyst in Europe and Asia to study high speed rail. Does ArcGIS online include HSR (such as the AVE in Spain or the TGV in France) in its analysis?
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1answer
819 views

Arcpy Intersect analysis function returns an error when using certain types of strings for input

In an arcpy for the intersect_analysis function, certain syntax works and others don't. What is the reason for this? Works: arcpy.Intersect_analysis("'D:\\Program Files (x86)\\ArcGIS\\data\\uscities....
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2answers
377 views

Which SRIDs to use for what tasks?

I try to understand the idea behind the different Spatial Reference Identifiers. I understand that the different SRIDs identify different projection views on the earth and that they are important for ...
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1answer
99 views

How to determine how many times an area was burnt? [duplicate]

In arcgis I want to find from various forests fires shp files how many times parts of a particular forest were burnt during the last 70 years. Is there a way to count overlapping polygons?
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2answers
40 views

Visually identifying areas where older poles predominate?

I have a dataset of 300,000 poles including a number of attributes including pole age. What I'd like to do, ideally, is be able to distinguish areas that have more old poles. Unfortunately I can't ...
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0answers
197 views

Calculating spread of invasive species using ArcGIS for Desktop?

I have ArcGIS Desktop Advanced and so far have completed the following; Used Supervised classification on a satellite image to identify the invasive species with field verification. I have converted ...
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 ...
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1answer
662 views

How to read GeoCSV with OGR?

I have a GeoCSV file which stores the geometry in a WKT formatted cell following this recommendation: "identifier","date","geom","value" "Dgf01","15.04.2013","POINT (52.404869 13.147457)","285" "...
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1answer
888 views

PostGIS polygon edge analysis (orientation, edge length)

I am rather new to the world of GIS and especially PostGIS, so please excuse me if the answer seems evident... I would like to do analysis on a number of buildings. One thing I am interested in is ...
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2answers
2k views

How to calculate Cost Surface Analysis in ArcGIS 10.x

I have about 10 points and I want to run Cost Surface Analysis. I’m trying to find what distance a person can walk in a given amount of time from a certain point (5-10 or 15 minutes). What procedure ...
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1answer
2k views

Extract values from raster by using polygons

I am working with multiple raster files that cover all of united states. The file format of the rasters - GeoTIFF. I have around 100 geotiffs that I need to process. Then I have another shapefile with ...
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0answers
766 views

How to calculate the average point spacing for a layer of points in QGIS?

I have a set of points and want to calculate the average point spacing for further analysis. ArcMap has the 3D Analyst Point File Information for this but I'm searching for an alternative in QGIS. ...
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1answer
142 views

non alignment of base layer and other vector layers

i'm sure you've encountered this problem repeatedly. i've tried all different methods. Enable on the fly crs transformation. go to settings and options to use crs data. go to properties and change ...
6
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1answer
448 views

Measuring Sinuosity of Walking Paths using QGIS?

I'm currently working on a project that examines the movement of consumers through different kinds of retail spaces in Central Asia – namely, bazaars versus supermarkets. I've equipped dozens of ...
4
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1answer
12k views

Calculate and add area of overlapping features within polygons

I have a polygon layer of watershed boundaries And a single multipart feature that contains all public lands for the state. I need to find the area of public lands within each watershed and add it ...
18
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3answers
1k views

Using GIS tools for non-geographical problems

Many other fields have visual/"spatial" problems that can potentially be solved with GIS tools. I know I've used GIS tools for the odd non-geographical task and was wondering how much this happens and ...
5
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1answer
634 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 ...
2
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1answer
41 views

How to compute areas where the value in one layer is smaller than in another layer?

I have two vector layers, one contains actual values (in this case % cover of native species), the other contains target vales of the same attribute. the polygons are not always of the same geometry. ...
3
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1answer
86 views

How to perform tree birthrate and mortality research with GIS [closed]

I'm using QGIS 2.6 and have 4 layers of polygons. Each of these polygons describes the outline of a tree, based on airborne imagery. My goal is to find the relations between every synchronously ...
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2answers
3k views

Calculating how many of certain feature lie within various buffer rings?

I am using ArcMap and I have a series of real estate parcels mapped along with a series of wind turbines. I have created multiple buffer rings around each real estate parcel with distances (0.5, 1, 1....
5
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2answers
395 views

QGIS calculates main soil type of polygons from another polygon layer

I've been working with qgis for a while but somehow I never fiured this out, so I thought it's time to ask. I have 2 shapefiles. a polygon layer from nearby fields (SHAPE1 (the red outlines)) a ...
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0answers
130 views

how to use line feature as stops input in network analyst?

I'm trying to build a certain route with network analyst on a Network Dataset. As an input to create the route I want to use line features. I am trying to do this with network analyst in ArcGIS 10.0 ...
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0answers
142 views

Get pixel values ascii 50 files

I'm working with photos from a camera. The camera is arranged to take NDVI values instead of RGB for each pixel. I have several folders with 50 pictures in each folder as '*.asc' files the pictures. ...
2
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1answer
56 views

Clip_Management seems to delete shapefile? [closed]

We have some python code that clips a very large shapefile for further processing. We can see the process create all the output files, but then just as the process is finishing, they get deleted. ...
3
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1answer
352 views

Performing equivalent of ArcGIS Identity_analysis (line with poly) using PostGIS?

I've got a section of arcpy code that I need to port PostGIS: Identity_analysis with the in_features being a line featureclass and the identity_features being a polygon featureclass. I'm primarily ...
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0answers
120 views

How to produce a simple ZTV/ZVI in openWind?

I'm struggling to get to grips with openWind. I need to produce a ZTV showing a 5km radius around the chimney of a proposed industrial development. I'm not sure of the height of the stack yet but for ...
9
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5answers
6k views

GIS analysis to find duplicate geometries

I have a big shapefile that contains all the buildings and houses of the town that I work in (approx. 90,000 features). The data of the buildings/houses are saved by the town's surveying engineers and ...
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1answer
183 views

Looping Summary Statistics on changing field name

I am trying to calculate summary statistics for a number of shapefiles, which is easy enough, but the field name for each shapefile is different. The field name is identical to the file name if that ...
5
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1answer
136 views

Is it possible, and if so how, to effectively classify vegetation types using false near infra red imagery?

Background : I use near infra-red imagery to delineate wetlands and water bodies with good success. It's also obvious to distinguish between new healthy vegetation and older growth and land areas with ...