0
votes
1answer
21 views

gdal_rasterize : getting area not in or touching polygon (options -at and -i)

I would like to capture the area that is not in a polygon (option -i) and that doesn't touch that polygon. gdal_rasterize -at will return the polygon + edges, but gdal_rasterize -at -i will not ...
1
vote
1answer
63 views

How to close spaces within a polygon in QGIS 2.2?

I have a shapefile displaying the borders of several city units. One of its polygons, however, had free space consisting of four vertices in it. I created another polygon inside the free space and ...
2
votes
1answer
84 views

Compute the area of a given polygon (in vector format) lying between specified lines of latitude

I have species distributions (in vector format) and I would like to calculate how much of the area for a given species distribution is within certain lines of latitude, such as temperate and tropic ...
4
votes
2answers
122 views

Converting shapefile to raster: Character attributes

I've got a shapefile that I would like to convert into a raster, but the trick is that the attribute I want a raster version of is character data. I'm familiar with geoprocessing using GDAL (in the ...
4
votes
3answers
128 views

How to shrink polygon on two sides?

I have a polygon which I know is a rectangle, although it may be at any orientation: I want to shrink this polygon by a third of the width from two sides, so that I just get the strip in the middle ...
2
votes
2answers
214 views

How to convert a shapefile to a grid file

I was wondering whether anyone might be able to tell me in layman's terms how to convert a polygon layer to a Grid file in ArcGIS 10.1 or ArcGIS 10.2?
0
votes
1answer
56 views

Can QGIS report/calculate areas/perimeters of individual polygon components within multipart shapefile?

Can QGIS report/calculate the areas/perimeters of individual polygon components within a multipart shapefile without using the "explode" vector tool to generate a new file? using QGIS 2.2.0 on ...
2
votes
2answers
62 views

How to select part of the polygon

I have a shapefile of the country. I need to select only percentage of that polygon for demonstration purposes. As an example, how to select 60% of polygon? I am using ArcGIS 9.3.
1
vote
1answer
68 views

draw multipart polygon with one surrounding border

As you can see on the image below, the waterbody is divided by the border line because it consists of several polygons. I could merge the polygon, but I dont want to change the shapefile. Is there ...
0
votes
1answer
262 views

How to extract geo data out of a polygon shape file into csv kwt [duplicate]

I have a polygon shape file that contains all the neighborhoods in the Netherlands. My aim is to export the neighborhoods and coordinates to csv file (KWT). Without success I tried (with QGIS) these ...
3
votes
1answer
235 views

remove land area from marine region polygons

In my pursuit to merge multiple polygons for the purpose of calculating the surface area of marine species distributions, using shapefiles from Marineregions, I am now trying to remove potential land ...
2
votes
3answers
116 views

Shapefile with overlapping polygons: calculate average values

I have a very big polygon shapefile with hundreds of features, often overlapping each other. Each of these features has a value stored in the attribute table. I simply need to calculate the average ...
1
vote
2answers
251 views

unionize intersections of merged polygons

[Updated quesion] I am using the following code to merged polygons from shapefiles for the purpose of calculating the surface area; library(maptools) library(rgdal) library(rgeos) #enter slots, ...
1
vote
1answer
85 views

Polygons not appearing when creating shapefile based on criteria using GDAL and Python (area calculated properly)

I am looping over the features of a shapefile containing multiple polygons. If certain criteria are met, I want to save the current feature in a new shapefile. I am doing this using GDAL 1.10.0 with ...
8
votes
2answers
306 views

Simple way to detect/select border polygons of a shapefile

I am looking for a simple way to detect/select border polygons of a shapefile. Border polygons are here polygons that are not completely surrounded by other polygons i.e. polygons located at the ...
0
votes
0answers
25 views

calculating mean and standard deviation for raster values using whole pixels within a polygon [duplicate]

i have a raster image and a corresponding shape file. i would like to calculate the statistics of the values within polygons which have a common attribute but only using pixels which are fully ...
1
vote
2answers
430 views

How many interior and exterior rings can a polygon have in a standard ArcGIS shapefile?

working with GDAL/OGR library and studying these two slides about geometries and vector data in the OGR library: slide 1 slide 2 I found that a polygon can have an exterior ring and lots of ...
0
votes
0answers
111 views

How to access vertices in a polygon layer using ogr library with c++

up to now I have tried these classes in order to extract the vertices of polygons: OGRPolygon : It doesn't have any method to get number of vertices, start point and end point. OGRLineString : ...
0
votes
1answer
153 views

Polygon grid shape file for landmass

I am interested in generating a polygon grid shape file for the landmass of the world. What I have presently is two tables in postgreSQL. Table 1: Coastal area shapefile ...
0
votes
1answer
53 views

Polygons Shrinking and Moving as if CRS Was Suddenly Out of Sync with Project

I long ago set the CRS for a linguistic geography project I'm working on involving Oklahoma data (EPSG:2836 - NAD83(HARN) / Oklahoma North), and I have been closely monitoring that the polygon ...
1
vote
1answer
135 views

Sum of point attributes inside hexagons using QgiS UI

I'm very new to Qgis so I would very much appreciate any help you can give me. I have a point shapefile that corresponds to locations of animals captured. I've joined a table to this shapefile with ...
2
votes
5answers
897 views

Counting road intersections and blocks

I have a shp file that consists of the road system of Mexico City. I would like to count the number of road intersections (crossings) and blocks (which I would define as a segment starting from one ...
5
votes
3answers
283 views

How to combine stacked polygons within a shapefile?

The image below shows my shp-file. Every polygon has the same transparent color. So a darker blue means, that several polygons are stacked! How do I cut every polygon with each other so no polygons ...
2
votes
1answer
282 views

R: How can I create a polygon from several polygons and a line?

I have some spatial objects that I want to combine, namely three polygons and a line. The ultimate goal is to create a polygon that I can overlay on an area of a map of administrative divisions of the ...
4
votes
3answers
287 views

How to subset X number of features from Shape file in QGIS

I'm looking for a means to take a rather large Shape file and split it out into separate, smaller shapefiles based on number of features. So for example, if I have a file with 1 million features, ...
1
vote
2answers
163 views

information from a shapefile to another shapefile

I am very new to GIS and learning by myself so what I'm about to ask is possibly quite basic. I am using QGIS. I have a shapefile, which categorizes areas (land cover) by numbers (corresponding to ...
1
vote
1answer
312 views

Is it possible to have self intersecting polygons in GML or shapefile?

GIS vector data for example GML or shapefile contains polygonal data. Lets assume, we have polygon A which has self-intersection which means that the edges in this polygon intersect with each other. ...
3
votes
2answers
2k views

How to edit Shapefile Attributes?

How might I go about exporting a polygon shapefile (e.g. CSV) so that attributes (not geometry) are editable by others, and importing it with the changed attributes (of which there are several columns ...
1
vote
1answer
221 views

Summarize polygon area using another polygon

I have a shapefile representing public/private lands in Montana. This is a multipart shapefile where I've simplified attributes so that #1==private and #0==public. Next I have a shapefile of ...
0
votes
1answer
344 views

In DIVA GIS how can I change the polygon co-ordinates of a .shp file?

I am using polygon layers from various sources to create species distribution maps however some of the layers have different polygon coordinates to others, therefore I cannot use them together as ...
2
votes
1answer
512 views

How to meassure the length of common edges between polygons?

I have a shapefile that contains several polygons which in fact represent the limits of several counties. My task is to find each length of each shared border. So in other words I want to know how ...
-1
votes
1answer
225 views

Finding the area of a polygon feature in a shapefile [closed]

Excuse the very simple question. How do i find the area of a selected polygon feature in a shapefile?
2
votes
1answer
147 views

How to digitize from a map with additional detail views?

I have a map with a river that includes islands within it. Some islands have a blown up version (detail views) outside of the river showing land ownership details. I would like to make polygons ...
2
votes
0answers
79 views

Determine which points fall within a 3D polygon and export this subset to a flat file

I am working in ArcMap 10 and will have a 3D representation of a zone of transmission. I would like to determine which GPS points fall within this polygon and then export this subset out to a flat ...
8
votes
5answers
1k views

How to get an ocean shapefile from a very detailed land area shapefile?

I am looking for a possibility to "invert" a shapefile. What I want to do is to convert a shapefile with the continents and islands into a shapefile that has water polygons. The existing ocean ...
1
vote
1answer
2k views

merging 2 polygon adjacent to each other using R

I have several shp files which are the components (or tiles) of a map, I have joint all these tiles together to have a large shp file. Then I realized some of the polygon is now splitted into 2 ...
10
votes
3answers
13k views

How to convert .shp to .csv including attributes AND geometry?

I have a .shp file with 60k+ entries, all of which are polygons with corresponding attributes (acreage totals, landowner names, tax ID #s, etc.). What I ultimately need is a .csv file with all of ...
9
votes
1answer
2k views

Instantiating spatial polygon without using a shape file in R

So, the usual way we read a shapefile in R is via the maptools package, like this: sfdata <- readShapeSpatial("/path/to/my/shapefile.shp", proj4string=CRS("+proj=longlat")) However, I have a use ...
5
votes
3answers
1k views

Why doesn't the split tool return any records in the attribute table?

I've been trying to split a large land use shapefile using a set of study area polygons as the split feature, but when the function finally finishes running (the land use dataset is quite large), all ...
3
votes
1answer
274 views

Polygon Shared Boundaries in GML

Last week I was told on a phone conference that GML supports shared boundaries in Polygon's. I have been unable to find any documenatation to substantiate the claim. Here is the situation: I have a ...
4
votes
1answer
3k views

Converting tax map polygons from Shapefile to table of map number and corner coordinates

Fairfax County, Virginia provides a Shapefile here which shows the boundaries of the tax maps as polygons. Each polygon simply consists of four corners, and what I'd like to do is create a table ...
2
votes
2answers
550 views

How to query data from a vector map (shapefile)?

We want to obtain the specific place of the boundaries of a shapefile. We want to be able to get the points of each polygon corresponding to a specific place in order to use these data in an ...
9
votes
4answers
6k views

using shapely: translating between Polygons and MultiPolygons

[EDIT: the solution to this was simply to use OGR to read shapefiles. See geographika's example.] In an ESRI shapefile, there is no distinction between Polygons and MultiPolygons. Furthermore, there ...
4
votes
5answers
1k views

Simplify shapefile parcel layer

I have a very large shapefile with over a million parcels within it. The problem I am having is that the polygons representing each parcel are very jagged. What I am looking for is a simple and fast ...