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Questions tagged [comparison]

The act of comparing or the process of being compared.

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1answer
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Looking for a trajectory similarity measure

For my final academic work I have developed a compression algorithm for GPS trajectories. I can estimate the quality of the spatio-temporal compression by computing the syncronized euclidean distance (...
10
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1answer
4k views

Identifying overlapping time intervals with two more criteria in R?

I have to check birds observations made over a longer period for duplicate/overlapping entries. Observers from different points (A,B,C) made observations and marked them on paper maps. Those lines ...
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5answers
20k views

Comparison of Open Source Desktop GIS Packages

I'm curious as to what comparisons are out there between different Open Source Desktop GIS software packages. I'm aware that there has been a QGIS and gvSIG comparison on this site but I am looking ...
9
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1answer
2k views

Comparison of three contour lines

I am looking for a way to spatially quantify the difference between three contour line shapefiles. More specifically, I have two elevation rasters which I intend to create contour lines from, but ...
9
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2answers
577 views

Tools to compare unversioned copies of geospatial data [closed]

My office has about 100 GB of geospatial data of varying forms (imagery, feature classes in geodatabases, LIDAR, tables, etc) that have gone somewhat unmanaged for the decade during which they were ...
8
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3answers
448 views

Efficient processing of difference between input data and database

I have an input dataset whose records will be appended to an existing database. Prior to being appended, the data will go through heavy, time-intensive processing. I want to filter out records from ...
8
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2answers
2k views

What are the pros and cons of using the ArcGIS Viewer for Flex vs. creating your own GIS application vs creating your own framework?

Simple question, but perhaps hard to answer. I have broken the title question into three distinct questions in order to clearly identify what we are considering for options each time we build an GIS ...
8
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2answers
2k views

PostGIS feature compare function?

I would like to be able to compare features in Layer 1 (source) to features in Layer 2 (updates to source) in order to see if any of the features geometry and/or attributes have changed. I would also ...
8
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2answers
317 views

How to efficiently (programmatically) determine whether two datasets have / don't have identical content?

Given: a geodatabase A that contains 100 datasets named a1 .. a100 a geodatabase B that contains 100 datasets named b1 .. b100 I want to programmatically (*) determine for each dataset pair (ai, bi) ...
7
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4answers
833 views

Comparing 2 vector files

I'm looking for a tool which compares two vector files (eg shapefiles). Eg 2 versions of a river network. Quite a lot of the records are equal, but some are different. A possible output would be eg a ...
7
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2answers
230 views

How to check what changed inside the updated shapefile?

I am using different shapefiles from open data in Switzerland. They have just updated the whole set. My question is: how to compared two layers (new and old version)? I would like to know the ...
7
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1answer
93 views

Why does 3d Bounding Box &&& check return true when I use ST_3DMakeBox?

I'm just wondering why this &&& is returning true when I use ST_3DMakeBox? SELECT ST_MakePoint(0,0,0) &&& ST_3DMakeBox( ST_MakePoint(-1,-1,-1), ST_MakePoint(1,1,-1) ); ...
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0answers
708 views

Landsat level-2 data comparison

I'm doing a temporal analysis of NDVI and temperature over 17 years, necessitating data from Landsat 5,7, & 8. I'm interested in using level-2 Landsat data available from https://espa.cr.usgs.gov/...
6
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1answer
3k views

How to compare 2000 Census block group data with 2010 block group data?

I want to calculate the percent change for median household income in Los Angeles at the block group level from 2000 to 2010. Someone told me I have to reaggregate 2000 block data to 2010 block group ...
6
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4answers
2k views

Basic .NET mapping components?

Which .NET mapping components are currently available? Focus is on desktop use and fairly basic mapping of SHP files (thematics etc.), not the more advanced GIS functionality (reprojections, clipping, ...
6
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3answers
205 views

What is the PostGIS 2.x equivalent of the pre-PostGIS 1.5 ~= operator?

Stemming from my other question: When would a PostGIS geometry compare using ~= return true when ST_Equals returns false?, what is the PostGIS 2.x equivalent of the pre-PostGIS 1.5 ~= operator? It ...
6
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3answers
2k views

Comparing choropleth maps statistically

I have several sets of choropleth maps showing ranges of poverty by census tract, each using a different poverty measure. All of the maps use the same categorical ranges to define poverty status. The ...
5
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3answers
656 views

In what data format should I export a (lat,long,alt) or (x,y,z) grid to be compatible with the largest number of GIS software?

I am new to GIS and developing an application that generates a 3D grid with (latitude, longitude, elevation) or (x, y, z) metric triplets, and I would like to add an exporting feature that ensures ...
5
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1answer
201 views

Difference between OSM regional extracts unexpectedly large

I want to create a difference (change file) between two Europe extracts from OSM data. The files I want to compare are: http://download.geofabrik.de/europe-180401.osm.pbf http://download.geofabrik.de/...
5
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3answers
398 views

Calculation based on features in shapefile

I hope I get the terminilogy right! Correct me if I mess something up. I need to perform some calculations for a scoring system for different habitat types. The Problem is that I have two different ...
5
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2answers
333 views

Different models, different contours: are they comparable?

I will get contour lines of electromagnetic field strength around power lines. The contours will be calculated by different agencies using different models. We need to check whether the resulting ...
5
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1answer
2k views

how to compare geometries (contains, within) in arcpy?

I am trying to use 2 geometry objects to check if a line is within a (rather complex) polygon. The geometry check always fails, even if the line is clearly within the polygon. I use the following code:...
5
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1answer
1k views

What is the Market share for open source web-GIS systems?

I would like to know the market share of 3 web-GIS systems, deegree, GeoServer, Geomajas). Which one is more popular? Are there any evaluations regarding the market share of open source web-GIS ...
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0answers
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Python vs R for analzing spatial data [closed]

I am relatively new to both the python and R programming languages, having a small amount of exposure to both. Which language has the edge when working with spatial data and when would you use R over ...
5
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0answers
397 views

Can Quantum GIS replace Proprietary GIS? [closed]

I’m an MSc GIS student in the final year of my studies. I’m researching for my dissertation project which is entitled ‘Can Quantum GIS replace Proprietary GIS in large organisations?’ I’m primarily ...
4
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1answer
896 views

comparison of Historical aerial photographs to today's satellite images

I'm working on a project in which I have to compare vegetation cover changes. So we have 1950's aerial photographs which must be compared to actual satellite images. Images must be properly adapted ...
4
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1answer
106 views

QGIS: Select point(s) in other layer with similar datetime value from selection

For the interpretation of bird observations, I need to identify the position on a GPS-track (gpx-files), from which the position of a bird observation (other gpx-waypoint layer) was recorded. The ...
4
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1answer
524 views

How to compare a classified raster dataset to another polygon dataset?

I am going to perform an unsupervised classification on my dataset and will get a map as a result. The objective is to rebuild an already existing map (of different soil types) with my new dataset. ...
3
votes
2answers
4k views

Python code to compare two fields in different feature layers?

I have two shapefiles which encompass 3897 features each. Corresponding shapefiles (village and watershed that flows into it) have the same ID (ws_id in one, OBJECTID in the other). Many watersheds ...
3
votes
2answers
863 views

How can a statistically significant difference between rasters be calculated?

so after some gruelling use of MaxEnt I have four occurrence probability rasters for the four quarters of the year, each one is about 70MB+. I want to test whether they are significantly different ...
3
votes
1answer
678 views

When would a PostGIS geometry compare using ~= return true when ST_Equals returns false?

I have a couple of featureclasses in a 10.2 geodatabase/PostgreSQL 9.2.2 database and I've been struggling with the FeatureCompare tool--it is telling me geometries are different on some features ...
3
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1answer
1k views

Does MySQL only support bounding boxes calculations instead of the real polygon geometry?

Within our company we are deciding which DBMS we will use to store spatial data. IT wants MySQL with the Spatial extension because there is already knowledge about handling MySQL DB. We are doing ...
3
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1answer
151 views

Appropriate Japan US comparison map

I would like to create a map in QGIS comparing the relative size and latitudes of Japan to the US. There are a few websites like mapfrappe which allow this using Google Maps, but I would like to be ...
3
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0answers
37 views

QGIS vs gvSIG: Update for 2019 [duplicate]

There were two posts from back in 2011 about the advantages of gvSIG and comparing QGIS and gvSIG. It's been 8 years since and I'm wondering if there might be an update since gvSIG and QGIS (at time ...
2
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1answer
1k views

How to use “this” Levenshtein Python code into ArcGIS 10

I need some help with this: First of all, I wanted to "Compare strings from two fields", and asking before at gis.stackexchange, in this post someone help me with this topic, referring me to a Python ...
2
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2answers
127 views

How to make two side by side maps match up in layout view in MapInfo?

I am working with two maps that have different thematic elements on each- in this case, I made two different columns to display the concentration of chemical found on that location. I display the ...
2
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1answer
3k views

How to compare string fields in the same table with ArcGIS 10

I don't know exactly if there is a tool for this or a maybe a python script could be more suitable. I want to compare string elements from a field (POI_NAME) with another string element in another ...
2
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1answer
998 views

Compare two Digital Elevation Model (DEM)

I would like to know what's the best method(s) to compare two DEMs without using any GUI soft like QGIS or ArcGIS. I'd like to do it in Python or C++, with GDAL or other similar lib. Does calculating ...
2
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1answer
167 views

Compare workspace schemas in Modelbuilder

My model has two model parameters: A file gdb workspace or sde workspace containing the data An empty "template" file gdb As the very first process in my model, I want to check if the schema of the ...
2
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1answer
592 views

How to compare a TIN and IDW-derived raster DEM quantitatively?

I'm a student and got the assignment to compare a TIN with a height raster 'quantitatively' and I'm not quite sure how to proceed. I tried subtracting the one from the other but it doesn't seem to be ...
2
votes
1answer
32 views

How to compare a 'predicted' layer with an 'actual' layer for the same study extent?

I have developed a vector layer which predicts which polygons are more or less likely to experience coral bleaching. I now have another vector layer with the same extent with actual coral bleaching ...
2
votes
1answer
592 views

Segment matching on a polyline

I have about 1000+ running routes which I can load into memory as polylines using latitude and longitude data captured from a running watch. From these polylines I would like to be able to identify ...
2
votes
1answer
147 views

resampled thematic map accuracy

I've generated a map of ecoregions based on some environmental data using a semi-supervised classification where I combined a statistical clustering with random forests to generate my map. I created ...
2
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1answer
590 views

Easiest way to find spatial differences between Polyline shapefiles

I run into this problem a lot. I have two polyline's and I need to test for Spatial differences in them. Usually I use Erase and I have my answer, but on this PC I now only have access to ArcGIS Basic ...
2
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0answers
46 views

Comparing multiple polyline shapefiles to single key file [closed]

I am working on a project where we are comparing participants' spatial memories. We take them through a circuit, then later in the lab they draw the route they traveled. I want to be able to compare ...
2
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0answers
91 views

Can 2 GIS layers which representing the same area be compared directly while having the same datum but different coordinate system?

My question is about how coordinate systems affect comparison of different layers - I have tried to refresh my memory about coordinate systems in GIS, but am still unsure about this situation. I am ...
2
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0answers
53 views

How successful are current metadata implementations in achieving its objectives

Metadata infrastructure is well established as an essential practice within the GIS community. Quoting from the FGDC: Metadata helps people who use geospatial data find the data they need and ...
2
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0answers
418 views

ArcGIS/arcpy: Geometry object comparison methods not working. Do they take z values into account?

I have an arcpy script that makes calculations based on an input PolygonZ feature class. What I need to do in several places in the script is test whether a point falls within a polygon in 2D. In ...
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vote
5answers
501 views

Looking for simple software to compare two Landsat Images

At uni I used ERDAS imagine to view two rasters at the same time and it had various viewers for comparing them. I'm looking for something that has a slider so that I can see the differences between ...
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3answers
22k views

Comparing differences in two polygon shapefiles using ArcGIS Desktop? [duplicate]

I am a new user to Arcmap 10. I've been trying to figure out how to compare two polygon shapefiles. I need to figure out what the difference is from 2007 - 2013 (increase/decrease) in a couple of ...