4
votes
0answers
74 views

What Does the Cell Value in a Composite Raster Mean?

When I make a composite raster in QGIS using the GRASS r.composite tool and then click on a certain cell I get these values in the blue/green/red/composite rasters: blue = 124 green = 124 red = 172 ...
4
votes
0answers
119 views

Most efficient way to intersect overlapping polylines

I have 4 multipart polyline shapefiles (download a sample dataset here). The geometries are identical, except for the length of segments in each shapefile. They represent 4 variables describing an ...
4
votes
0answers
92 views

Postgis database query optimisation

I have a set of rasters in DTED format which I load into postgis database using raster2pgsql command line tool. Each of rasters is simply stored in a row and described by rid and a value of raster ...
4
votes
0answers
260 views

ArcObjects .NET - How to close/release FeatureClass, Workspace, Factory

I have a long-running process. I want to prevent resource leaks or rogue database connections. At intervals during the process I want to do this: get an ArcSDE (Oracle) workspace factory open a ...
4
votes
0answers
35 views

Access multiple rasters with GeoServer

I am curious if anyone knows if, and how, it would be possible to configure GeoServer to provide download (GetCoverage) capabilities to multiple adjacent rasters. A GeoServer mosaic comes close, but ...
4
votes
0answers
86 views

Adding data from PostgreSQL to Query Layer of ArcGIS for Desktop warns that given coordinate references are incompatible?

When adding data from PostgreSQL in a Query Layer I get the warning "The given coordinate references are incompatible" I have added many other layers with the same properties no problems, but I have ...
4
votes
0answers
103 views

Alternative to Delete Polygons And Extend Lines of Production Mapping?

Maybe someone knows an alternative for the Delete Polygons And Extend Lines (Production Mapping) tool or a simple way to achieve the same result but without requiring a Production Mapping license?
4
votes
0answers
76 views

Create a Shape file from Sql dump file

I am trying to map data by querying a table called xyz. I need to show the the_geom data on the map. I have below query in my mapserver .map file: DATA "the_geom from xyz using unique id using ...
4
votes
0answers
107 views

Using Traffic with Network Analyst VRP

To the best of my understanding, setting a specific day under Analysis Settings for the VRP uses the Routing_ND historic traffic information. Is there some step I'm missing to enable traffic? I've ...
4
votes
0answers
88 views

Interpolating species data from sample points in a small area

I have sample data from a small site (10 acres) which shows the number of occurrences of a particular species of snail over two sampling periods (fall and spring sampling). I want to try and ...
4
votes
0answers
56 views

Null Values in Geographically Weighted Regression Analysis

Some of my explanatory variables have a few null values for certain polygons. Can GWR handle these, or should I remove the whole polygon and all data (dep, ind variables for that particular polygon)? ...
4
votes
0answers
61 views

How to calculate an Illumination raster for fire ignition danger analysis?

I am doing a fire ignition danger analysis using this equation that I found in Millington (2012) http://www.jmecology.com/wp-content/uploads/2014/03/33-42-MILLINGTON.pdf IR = 4H + 3V + 2I – E Where: ...
4
votes
0answers
154 views

PostGIS “Overlay” Style Union, not “Dissolve” Style

I'm trying to use PostGIS to do a 'union' of polygons. When I Googled "PostGIS Union", I found the ST_Union function, which performs what I would call a 'dissolve,' not a Union. What I actually want ...
4
votes
0answers
176 views

Performing buffering and intersection with script in PyQGIS

I wrote a script that performs the intersection of two layers: The first Layer -> layer1, represents the rivers The second Layer -> layer2, represents a set of circular dots distributed in a ...
4
votes
0answers
99 views

Rotating annotation by angle using center point of annotations (with baseline alignment) in ArcMap

Is it possible to rotate annotation (in ESRI Annotation FeatureClass) by angle so that new position would be calculated based on annotation center point (not alignment, as it is set to baseline, ...
4
votes
0answers
99 views

GeoServer ImageMosaic PostGIS index update

I use GeoServer where I created an ImageMosaic storage following this manual. When I create new datastore, all *.tif files are indexed into DB (PostgreSQL with PostGIS). How can I create new index in ...
4
votes
0answers
170 views

ArcObjects : Out of Server Memory when reconciling a large edit session

One of our users has been periodically experiencing 'Out of Server Memory' errors with ArcSDE 10.0 when trying to reconcile a large edit session. VMware ESX Instance: Windows Server 2008 R2 ...
4
votes
0answers
269 views

How to calculate the average distance among set of points as measure of closeness

I have three series (or tables) of points in PostGIS which I want to compare. I would like to know how "close" each series is when compared to the other two. In other words I would need some measure ...
4
votes
0answers
180 views

How do I parse the file format for attributes in Raster Product Format (RPF) maps and imagery?

I'm trying to implement an open-source NITF reader (using only java, no external libraries such as GDAL or NITRO), and its mostly going OK. However I'm having trouble understanding the RPF extensions, ...
4
votes
0answers
190 views

Has anyone used ArcGIS for 'automatically' detecting lineaments from a high-resolution (1m) DEM?

I have a set of DEM's produced from LIDAR data. I am wondering if anyone is familiar with or knew of any published research papers which looked at (semi-)automatically detecting lineaments /or ...
4
votes
0answers
267 views

How to fix “Raster layer: Provider is not valid” error when loading PostGIS rasters?

I compiled and installed the current QGIS master as usual and I imported some raster data into my postgres 9.3 database with postgis 2.0.2 extension. Whenever I try to import the raster data into qgis ...
4
votes
0answers
145 views

How do I simplify the straight sections of (multi)Linestring in PostGres/PostGis leaving the curved sections untouched

I have (multi)linestrings containing upwards of 5000 points and I want to perform two simplifications possibly using Ramer Douglas Peucker or alternative methods in PostGis The (multi)linestrings ...
4
votes
0answers
648 views

How to use the linear referencing plugin?

I need a guide how to use this plugin properly, I'm a newbie on PostGIS and I'm trying to use the linear referencing plugin of QGIS. I've created a database on postgreSQL with the postGIS extension ...
4
votes
0answers
215 views

QGIS: How to reverse vertex ordering in polygons

I am working with an Oracle spatial connection in QGIS through which I am accessing and editing a vector layer. I find that when I edit a geometry, the vertex ordering is reversed (to clockwise in the ...
4
votes
0answers
419 views

Hibernate Spatial - 'Invalid endian flag value encountered' Exception

I'm trying to run a simple query in Hibernate Spatial 4.0 on PostgreSQL 9.3. I have a number of objects in a table with latitude/longitude values, and I'm trying to query objects that fall within a ...
4
votes
0answers
109 views

Why are date vaules displaying a trailing 'Z' when layers are published with Geoserver and a PostGIS data store?

I have published various layers using Geoserver 2.2.x with a PostGIS 2.0.1 (PostgreSQL 9.1.x) data store. Fields that only have date values and not time/timestamp related values are stored as date. ...
4
votes
0answers
120 views

Add attribute table to a raster in postGIS

I would like to add attributes to a raster stored in a postgis database. I use the following command to insert the raster in the database: raster2pgsql -s 4236 -I -C -M ...
4
votes
0answers
437 views

Finding poi using st_dwithin in postgis

I am not familiar with gis or writing sql, so my understanding in this field is lacking. I have a hundreds of lat/lng geographic coordinates stored in a single table called Places like this: ID | ...
4
votes
0answers
220 views

QGIS does not read ESRI Geodatabase correctly

I have a geodatabase from the EPA that does not seem to me reading correctly with Quantum GIS. QGIS Version 1.8.0 (Lisboa) and GDAL/OGR 1.9.2 When I open the attribute table the first two columns ...
4
votes
0answers
393 views

Find points that fall within a radius using Hibernate Spatial

I am using hibernate spatial and postgis and i want to find the points that fall within a certain radius. Using this SQL: SELECT name FROM institution WHERE ...
4
votes
0answers
237 views

Constructing a Voronoi diagram using a complicated travel time metric

I have in my possession four sets of shapefiles: 1. Locations (points), around 1000 2. Roads (lines), each road has a speed attribute 3. Terrain (polygons), each zone also has a speed attribute 4. ...
4
votes
0answers
205 views

How to write an address search plugin?

I am migrating some users from MapInfo to QGIS, and before they sign off on it, they want a very simple address search in the same way that we currently have one working in MapBasic. I;ve been having ...
4
votes
0answers
265 views

GPS data based track/trip calculation algorithm available?

Currently I'm receiving position data of moving assets every 90 or 120 seconds (depending on the asset). What I'd like to achieve now is to detect standstill and movement phases (tracks/trips) on the ...
4
votes
0answers
303 views

Tilestache/Mapnik: Is it possible to create dynamically filtered layers?

I'm using Tilestache to generate two layers with the mapnik and mapnik grid providers, and it's working great! However, I want users to be able to filter the data over many (more than ten) ...
4
votes
0answers
355 views

What traits identify 2D, 2.5D, 3D geometries, and how can you convert downward, such as from 2.5D to 2D?

In answering this question, posed by @Burton449, I came to realize I don't have a definitive grasp on what distinguishes 2D, 2.5D, and 3D geometries. I certainly realize Z/elevation values are ...
4
votes
0answers
395 views

Extracting x,y,z values from a postgis linestring to python using ogr

I am trying to load a postgis linestring into python (using ST_DumpPoints) and extracting x,y,z coordinates, which is working but extremely slow..and if i mean slow, i really mean it (yes, it takes ...
4
votes
0answers
817 views

Microsoft Surface vs. iPad for mapping

I was recently introduced to the Avenza PDF app for iPad and I've been using it in the company I work for to help our field crews find their way around, and record waypoints and tracks. The app takes ...
4
votes
0answers
218 views

building larger polygons from smaller ones *without* a common id in PostGIS

I am looking for a means, using PostGIS, of reconstituting a set of polygons from tens of thousands of smaller polygon 'pieces'. This is a simplified example, with the pieces shaded: Unfortunately ...
4
votes
0answers
220 views

PostGIS 2.0 st_geomfromgml using LineString fails with invalid GML representation

I am attempting to insert a geometry into a table using the st_geomfromgml function. The GML is being sourced from a Geoserver WFS request. The function call looks like this ...
4
votes
0answers
226 views

How do I clip Geojson FeatureCollection with another Geojson polygon

I have a GeoJSON file that contains one FeatureCollection with a bunch of features that are polygons. I also have the boundary of the continental USA in another GeoJSON file. I'd like to clip the ...
4
votes
0answers
1k views

How to Export a Shapefile as KML Using R

All, I have exported an ESRI shapefile (polygon) to KML using R, but the resulting layer shows only the outer extent of the polygon. How can I fill in the area with a color? Any help is greatly ...
4
votes
0answers
167 views

create minimal spanning tree using table of distances between nodes rather than TSP

I am working on a transportation (linear programming) problem. Each potential solution also requires checking the distance of approx 20,000 routes with 5 to 15 nodes per route. Calculating the ...
4
votes
0answers
264 views

Display a color ramp legend (of a vector layer) in the qgis map composer

I would like to have a color ramp instead of 10 categories of color when displaying my vector layer in the map composer of QGIS. Is it possible ? Thank you in advance
4
votes
0answers
657 views

How to modify the edit widget in ESRI flex viewer 3.0?

I am running ArcGIS Server 10.0 (sp2) on Windows server 2008 64-bit with IIS 7. I am using the ESRI flex viewer version 3.0. I have created a feature layer and published it as a rest service and ...
4
votes
0answers
157 views

Advanced GMaps directions

I try to create an application for taxis. The application will be GMap based. On the map will be marked the region in which the taxi driver is working in. The region will be a polygon designed by ...
4
votes
0answers
103 views

What is the structure of Standard Interchange Format (SIF) used by spatial data providers?

What is the structure of Standard Interchange Format(SIF) used by navteq and other spatial data providers? Any documentation/sample files? Is there a SIF parser available in C/C++/Java/PHP ?
4
votes
0answers
92 views

How to set ArcMap 10 attribute dialog split orientation to horizontal by default

When you open ArcMap 10, and open the attribute window (editor toolbar), the attribute dialog is split vertically. You can press the toggle button to split the dialog horizontally. I always use it ...
4
votes
0answers
267 views

How to apply ArcGIS time slider on Multiple Data Frames at once?

Is there a way to use the Time Slider on multiple data frames simultaneously? Example: My Dataframe 1 shows precipitation values over an area and DataFrame 2 shows corresponding temperature.. I want ...
4
votes
0answers
187 views

Is PgRouting DARP Function still being supported?

I'm asking this, because I need some tool to solve a DARP problem. After researching I found PgRouting had included this functionality in one of its branches. But after installing it, getting stuck ...
4
votes
0answers
562 views

ArcGIS Cost Path Analysis - How Is Arcpy Cost Path Analysis Tool So Much Faster Than ArcObjects

Although I love slinging some python to create geoprocessing scripts/services, I was under the impression that using ArcObjects to do the equivalent operation(s) will have better performance. I've ...

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