Tagged Questions

4
votes
1answer
54 views

Raster to vector with gaps in Landsat ETM

I need to find size of water area from a raster (jpg) using QGIS 1.8.0-Lisboa. The raster is a Landsat image with gaps of data in it. I used Polygonize, but the output file shows wrong polygon size ...
3
votes
1answer
91 views

Visualizing Spatial Query

I'm new to GIS applications and trying to figure out what options I have for visualizing spatial query results that combine raster and vector data using OpenLayers/GeoExt/GeoServer/PostGIS. A ...
4
votes
0answers
69 views

Assigning costs to a road network : use raster or vector?

I have a road network in a PostGis database (db_routing). In another database (db_environment), I have some spatial features of the surrounding environment (trees as points and water bodies as ...
3
votes
1answer
396 views

What is the difference between Vector and Raster data models? [duplicate]

From: http://support.esri.com/en/knowledgebase/GISDictionary/term/vector%20data%20model vector data model: [data models] A representation of the world using points, lines, and polygons. Vector ...
1
vote
1answer
82 views

How to invert polygons (or other options for exterior styling)?

I have a shapefile containing many polygons that I want to use to mask a raster. I have tried gdalwarp -cutline <shapefile> -crop_to_cutline -srcnodata -9999 -dstnodata -9999 ...
3
votes
2answers
101 views

Overlay Vector Layer on Raster Layer

How can I overlay a Vector Layer on a Raster Layer and assign NoData Values on the Raster where the Vector Layer does not cover the Raster Layer? (preferable with ArcGIS)
1
vote
1answer
80 views

How to convert a shapefile polygon to raster in C#

Does anybody know a way to convert a polygon (vector) in a shapefile to raster data WITHOUT using ArcGIS Explorer Desktop? Is there a way to do this 'progmatically' in C# (WPF with ArcGIS runtime ...
2
votes
0answers
35 views

Is there a tool for automated quality assurance for vector data captured on raster data?

I wonder whether is any tool(or script) in ArcGIS or QGIS which allows to make an automated quality assurance for vector data captured on raster data? vector data on binary raster:
0
votes
0answers
22 views

Polygonize Raster to Vector Error [duplicate]

I have a problem when I am trying to Polygonize (Raster To Vector). I have a Corine map with 44 different land uses. I run a query and I save the selected areas with Bands 0 and 1. Now I am trying to ...
1
vote
1answer
57 views

How do I create rendered vector field in qgis

Perhaps I am misunderstanding the "vector field renderer" and "VectFieldCalc" plugins, but I have no idea how to make a vector field of arrows, with directions and magnitude. I have the data loaded ...
1
vote
1answer
72 views

Set certain amount of pixels to 1 inside of a polygon (GRASS)

I have a rather coarse vector map with polygons and want to calculate a (sufficiently) finer raster map defined by spatial extension and resolution. Every polygon of the vector map has a value ...
5
votes
1answer
91 views

GDAL/OGR Determine if dataset is raster or vector

I am writing a script using the GDAL/OGR Python bindings and it is possible that the user may provide a raster dataset or a vector dataset as input. If the user provides a vector dataset, the script ...
2
votes
0answers
94 views

how to align vector and raster images? [closed]

How to align vector and raster images? For example vector images will be static/rigid and raster image will be morphable. For example I manually do initial guess and algorithm must converge to optimal ...
3
votes
1answer
100 views

Creating a vector based design from a raster database

I have a raster table that I've created using Postgis raster. It has 365 records and the table looks like this: +-----+------------+---------+------------+ | rid | rast |filename |date_of data| ...
2
votes
1answer
71 views

From Raster to Masked and Filtered Polygon Vector

I have a set of rasters (geologic risk) from which I want to extract zones with a specific color, clipping them with a polygon (administrative borders), outputting a shapefile. I'm using QGis (and ...
3
votes
0answers
75 views

Is there a way to create raster by interpolating point values using GeoTools 8.2?

im new in using GeoTools (8.2). I was able to create shp from asc file which contains my data. Now my question is is there a simple way to create (interpolate) a simple shapefile (only points) to ...
4
votes
2answers
244 views

Spatial query of raster data

I have population distribution data as a raster layer and exposure contours as vector (polygon) layers. What I'd like to do is use the vector layer to estimate the population indicated from the raster ...
7
votes
2answers
142 views

How to remove long linear strips from polygons?

I have a polygon layer representing impervious land cover. This was taken from a land cover raster dataset. The impervious data represents all impervious surface that is not buildings or roads. I ...
5
votes
3answers
1k views

Extract Raster Value into Polygon Attribute

I have Raster Data for a State which has Elevation Data in its pixels. I also have Vector layer which has the 300 divisions of State. what I need is, I want to get the average elevation value of ...
2
votes
0answers
114 views

Overlay Shapefile onto Geotiff

I have a Geotiff map and I want to overlay a Shapefile onto it. Ideally I want to specify a 'nice' style for the polygons e.g. have them opaque (for now all polygons should be the same). I want to ...
3
votes
3answers
599 views

How to sum raster image values with vector overlay

I'm new to this and haven't been able to figure out how to do this on my own. Here's what I want to do ... I have two files: a raster image of land use data and a vector-based shapefile of my ...
2
votes
1answer
82 views

Is there anywhere that I can obtain global UV data in either raster or vector format?

I'm looking for some UV data (currently with no spatial or temporal resolutions in mind, but ideally split into UV-A and UV-B) for the whole earth. Can anyone recommend a source for data like this or ...
0
votes
1answer
110 views

QGis : superimpose 2 rasters georeferenced (adjustment)

I am pretty new in QGis and I encounter the following problem. I have 2 rasters, let's say, "cadaster" and "tranchot". The raster "tranchot" was georeferenced from the raster "cadaster" with QGis. ...
2
votes
1answer
359 views

Loading Raster and vector data In MapGuide using Maestro

I am new to Mapguide , working on it for my summer Internship.I have Installed it perfectly. Now the task is to load vector data and Raster data in map Guide (mainly have to load *.shp files and *.tif ...
4
votes
1answer
194 views

Generate centroids for vector polygons based on raster and land-use data using QGIS

Although QGIS has the ability to generate centroids for polygons, I am not sure how to generate centroids based on land-use development using raster data. Here's an example of what I'm trying to do: ...
0
votes
4answers
1k views

OpenLayers (allOverlays): Vector layer not rendered without raster layer beneath it

This is another newbie question. I'm trying to create a map using OpenLayers that comprises only of vector layers from a WFS server. However, I'm thwarted because my vector layer won't render unless ...
5
votes
3answers
5k views

How to convert a vector layer to raster?

In qgis in the raster menu there is an item "convert vector to raster". This behaves strangely - I do not understand how it is supposed to work. I can select a vector file, an attribute and an ...
4
votes
3answers
1k views

How to combine information from raster and vector layers?

in QGIS I have 1 raster-layer (elevation) and 1 vector-layer (administrative units). Now I would like to be able to query one of the administrative units and see the mean and min/max of the elevation ...
4
votes
2answers
340 views

Is it possible to generate a vector polygon from a polygon on a raster image?

I have a raster map which I have extracted from a government report providing flood extent return frequencies. I want to 'snatch' these flood extent polygons (i.e. convert to vector) and I was ...
4
votes
2answers
1k views

How to clip a vector feature to the extent of an existing raster dataset using arcpy

I have a clipped raster dataset with polylines (from the contour tool) overlayed (see attached). I am trying to clip the polylines to the extent of the raster dataset, which seems simple enough, but ...
2
votes
1answer
354 views

Select vectors overlapping a raster

I have a raster layer with travel times from a specified point in my city's downtown. What I'd like to do is select all of the census blocks that lie at least partially within 45 minutes of downtown ...
3
votes
1answer
318 views

turning multiple vector layers into one raster in arcgis 9.3.1

I want to make a raster out of the multitier view I have in ArcMap 9.3.1 . The layers in my ArcMap come from several datasets. I know there is a 'Feature to Raster' tool, but it converts one layer at ...
5
votes
2answers
143 views

Vectorize cell boundaries in GRASS

I need to vectorize the cell boundaries of a raster map and I have forgotten how to do this. For instance, if I have a raster map of a region that is just map=1 with a cell size of 500m, I would ...
1
vote
0answers
133 views

Can I overlay layers in Dealul Piscului 1970 and WGS84 in QGIS?

I have a 10 Gb ECW file (mosaic of a whole county) that is in Oblique Stereographic projection with Datum: Dealul Piscului 1970. The problem was that no matter the Default CRS for new project was, ...
1
vote
2answers
610 views

Tools/processes that avoid the need for raster to vector converstion?

A "brute force" method of solving GIS problems that involve acquiring values from raster cells and storing them on spatially overlapping vector features is to first convert the raster to a vector. The ...
1
vote
2answers
1k views

How to set cell size for vector to raster conversion in QGIS GRASS plugin?

I'm converting a vector (loaded in GRASS plugin in QGIS (1.7.0.-wroclaw) and would like to convert this to a raster with a defined cell size. At the same time I need a value from the attribute tabel ...
6
votes
1answer
152 views

Finding largest number of observations within a given radius

I have the following problem: Given the location of insured properties (say houses with fire insurance), i have to find the largest sum of insured values which fit into a 300m radius. Now, my first ...
8
votes
2answers
518 views

How to convert a vector boundary to a raster map?

I need to output a PNG file of a raster map overlayed with boundaries present in a vector map. The problem is, the r.out.png script only exports a raster map. My boundaries are in a vector format. ...
13
votes
3answers
8k views

How to clip a raster with vector boundaries?

I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data. How can ...
4
votes
3answers
3k views

Find the nearest raster cell value based on a vector point

I have two layers in ArcGIS: One is a vector point and the other is a raster layer. I want to append the value of the raster data grid to the vector point. The problem is the vector point is away from ...
4
votes
5answers
458 views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
22
votes
6answers
28k views

What are Raster and Vector data in GIS and when to use?

What are raster and vector data in the GIS context? In general terms what applications, processes, or analysis are each suited for? (And not suited for!) In answering someone's question today, I ...
5
votes
3answers
2k views

Creating a raster surface of overlaps from vector polygon shapefiles?

Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it ...
0
votes
0answers
538 views

How to select an area in a raster map that is compared with another raster map? (intersection of two raster maps) [closed]

I have raster map A=elevation values and raster map B=raster with colors (each color represents a polygon boundary. raster map B is created with the use of v.to.rast) I want to select the part of ...
1
vote
1answer
700 views

How to select a raster file that is under a polygon in a vector file?

I am using: v.db.select map=PHL_adm1 where=NAME_1='Bulacan' My vector map is over the raster map. I want to select the part of the raster map under the polygon(NAME_1='Bulacan') of a vector. Is it ...
1
vote
1answer
1k views

How to combine a vector and a raster file?

I want to combine a raster and a vector file. After combining, can I query on the resulting map to obtain a specific area? How?
3
votes
1answer
397 views

How to sensibly digitise this raster, scriptably, in ArcGIS

I have the raster below which I want to convert to a set of vector lines: As you can see, there are small breaks in the lines and some bits are double-width. I want to be able to reliably import ...
-5
votes
3answers
819 views

Delivering map tiles in real-time without caching?

I am wondering how useful would you find to have a way to deliver map tiles quickly over the web without worrying about caching or seeding them? With raster map engines we know that this is a ...
4
votes
5answers
3k views

Problems merging DEMs or other raster datasets? Clipping Raster dataset to vector line?

I have two DEMs that I am going create a hillshade from, and ultimately want one hillshade clipped to a county boundary. I am running into a couple problems, though. When I try to merge the two ...