On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.
3
votes
2answers
204 views
How to convert polygon layer to txt files?
Is there any way to convert polygons that do not have coordinates in the attribute table to a txt file with coordinates. I will be using the txt file in a different software (not ArcGIS), so I need ...
2
votes
2answers
97 views
How can a style be set on a specific polygon using OpenLayers?
Using a polygon id, I want to highlight a polygon, while the mouse is outside of the map area. I can identify the polygon using the following approach:
x = 53;
for(i=0; ...
2
votes
1answer
562 views
How can GeoJson polygons be colored programmatically using OpenLayers?
I'm experimenting with dynamically setting the color values of a geojson polygon. In my geojson file, there is an attribute for each polygon called pop_den. I am trying to update the fillcolor of the ...
5
votes
3answers
355 views
How do I use polygons to apply a unique value to all raster cells within those polygons?
In ArcGIS 9.3, I have a raster file that I would like to "mask" with polygons, giving a single value to all the raster cells that overlap the polygons. How can I do this? Here's a screen shot, where ...
2
votes
3answers
218 views
Zonal Statistics as table creates output but some are Null
Here is my newest issue:
I have temperature as a raster file and different ecoregions of a province as polygons.
What I want to do is calculate the mean temperature per ecoregion.
I succeeded in ...
3
votes
1answer
658 views
Polygon to Raster Tool Problem
I am trying to create a raster data set from county level polygon data for the US. I have successfully created one raster from a dataset, but when attempting another, it does not work. I am ...
6
votes
2answers
417 views
Converting point sets to polygon boundaries
I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
1
vote
0answers
56 views
footprint polygon from raster data with postgis
how can I create a polygon, containing the actual outlines (aka footprint) of a raster file with postgis?
I just need the outlines of the data containing parts of the raster.
ST_PixelAsPolygon ...
1
vote
0answers
77 views
How to construct a line from points in pyshp?
I am reading a shapefile for a pipeline and what I've noticed is that if I just draw a line from one point to the next (in the order I read them), there will be points where the line terminates, and ...
1
vote
2answers
178 views
One Polygon Joining to Database with Many matching records
Using ArcMap 10.1.
Is this possible to have one polygon and join to a database/excel with many matching records?
I would like to have 1 polygon but match to 100 corresponding records in a table. When ...
5
votes
1answer
70 views
How do you edit a stack of polygons simultaneously?
Using ArcMap 10.1.
Lets say you have 100 polygons that all are in the exact same shape and in the exact same place. They appear to be one polygon. How would you edit the shape of all 100 at the same ...
6
votes
1answer
192 views
How to draw shapes with highest possible decimal accuracy
I am trying to read input of lat and long to draw the shape based on condition.The input is standard array of lat and long with 15 decimal accuracy. I am realizing - I am loosing some decimal accuracy ...
9
votes
1answer
330 views
Self intersections for polygons, howto solve?
I have a question about repairing a self intersecting polygon shapefile. I have a shapefile containing Polygons (ZM) which has self intersecting features. If I use the "repair Geometry" tool, it finds ...
1
vote
1answer
164 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. ...
2
votes
1answer
104 views
How to join attributes of donut polygon to hole polygon in ArcGIS?
First of all I'm completely new to the realm of GIS and ArcGIS.
Basically I need a reliable way to determine a donut hole's containing donut for a few hundred thousand polygons (where the donut holes ...
4
votes
1answer
336 views
Polygon label repeated for each tile
I'm using the standalone GeoWebCache to serv tiles from a remote GeoServer. My problem is that the polygon label is added to each one of the tiles served, instead of only once in the polygon centroid.
...
2
votes
2answers
192 views
Creating Long & Lat for Polygons
I have a base map image with micro regions, however in the attribute table there is no information regarding the long & lat. Is there a way I can create a long & lat for each micro region?
...
3
votes
1answer
146 views
ESRI/ArcGIS draw protractor
I am using ArcGIS maps and trying to follow JS API. I am trying to understand how can I add a protractor on the map which will help in angles while drawing polygons. I understand I could add a Feature ...
3
votes
2answers
442 views
How to clip polygons with a fishnet layer?
I have a layer with multiple polygons (input) and a fishnet layer in polygon (clip layer).
I want to clip the multiple polygons with the fishnet to be able to calculate how big portion of the input ...
3
votes
1answer
373 views
How do you convert raster to polygon while avoiding small polygons
I intend to convert a raster to several polygons, but I want to ignore too small polygons, and just keep larger polygon. How can I do that?
Thanks in advance!
3
votes
1answer
313 views
adding polygon to database in openlayers
I want to add a polygon to the database. I used the following code. The problem is that I am to able to save in database. Whatever polygon I draw on map it gets save temporary and as soon as I reload ...
4
votes
1answer
948 views
How do I change the polygon fill color and border color for SpatialPolygons objects?
I have SpatialPolygons or SpatialPolygonsDataFrames which I'd like to plot. How do I change the color using the three plotting systems in R (base graphics, lattice graphics, and ggplot2)?
Example ...
2
votes
1answer
79 views
Compiling a list of units that border each other
I have a shapefile of U.S. counties. I am interested in compiling a list of those that border each other.
In particular, I am interested in those that border each other but are in different states. ...
0
votes
1answer
507 views
How to divide polygon layer into multiple layers by values in attribute table column in ArcGIS 10.1
I have polygon layer with multiple types of area (forest, grass, and many more), and I´d like to divide this layer into many layers by the area type.
I´ve tried Split function but I receive an error ...
1
vote
0answers
146 views
When I finish drawing a polygon, it disappears again (although appearing in my attribute table)
I'm working with Quantum GIS at this moment. And as the title says, when I finish drawing a polygon, it disappears again. The new object does appear in my attribute table and in the legend/'filling of ...
4
votes
1answer
197 views
Iterate features on SpatialPolygonsDataFrame in R
I have a SpatialPolygonsDataFrame object. Is there way to use apply on this object rather than using a for loop to iterate features in this object?
0
votes
1answer
111 views
How to add a label of a point to a polygon
i have several polygons with in each polygon a point with a label (number).
I want to add the label in the polygon to the attribute-table of the polygon it belongs to.
3
votes
2answers
621 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 ...
3
votes
0answers
126 views
Rgeos drops associated values when intersecting polygons
I am trying to intersect two SpatialPolygonsDataFrames and get a SpatialPolygonsDataFrame as the result. Unfortunately, using the gIntersection function from rgeos (which works impressively quickly ...
6
votes
2answers
1k views
Create a polygon layer from point data
I'm currently using QGIS 1.8.0
I would like to create a polygon layer from a point dataset, where the size of the polygons relates to the resolution of the grid reference.
The ultimate aim would be ...
4
votes
1answer
2k views
Arcgis 10: Point layer, polygon line layer, draw points to the nearest polygon point or other nearest line?
I have been using arcGIS for a while now but I often get frustrated with it :(
I have version 10.0 arcGIS and I'm have two layers
1) Point data (building locations)
2) a polygon shape file (outline ...
4
votes
1answer
272 views
How to automate the drawing of polygons (square) around a number of points in QGIS?
In QGIS (or alternatively any other scripting + GIS stack), how can I automate drawing a 100km x 100km square around a number of points, with the point being dead in the center?
I'd need to loop ...
5
votes
2answers
270 views
How to enclose clustered points with polygon?
I have a raster with forest (1), no forest (2) data. "1" is represent single/few trees and there is gaps between them. I want to create a polygon around these trees to a forest map. It is not a dense ...
1
vote
1answer
131 views
gdal_rasterize -at function still won't capture covered pixels properly
I'm currently using the gdal_rasterize tool in bash. My code looks like this:
gdal_rasterize -l $(basename $file .shp) -burn 1 -a_nodata 0 -te -180 -90 180 90 -tr 0.1 0.01 -at -ot Byte $file ...
1
vote
2answers
275 views
Assign unique ID to each polygon
I feel like this should be really simple and I am missing something. All I wish to do is assign a unique ID to each polygon since I have multiple identical FID values. In MS excel I would simply type ...
2
votes
1answer
443 views
Identify duplicate polygons to enable removal after reviewing attributes
I wish to label overlapping polygons so that I can manually locate each overlap then review the attributes of each overlapping polygon and decide which suite of attributes to maintain before ...
3
votes
2answers
77 views
Dissolve column based on attribute in another column
I have 3 columns within a polygon layer I'm working with.
Column 1 = Landowner, 3 different values
Column 2 = Parcel, N different values
Column 3 = Management type, 5 different values
I would like ...
1
vote
1answer
97 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 ...
7
votes
2answers
882 views
How to check Topology in QGIS?
I have two Shapefiles with Polygons ( City and Forerst)
Is there a Plugin who is able check the topology (QGIS)? Like "Knots do not overlap" or something like that? I dont want that they overlap.
...
7
votes
1answer
386 views
Advanced Polygon and Parcel Splitting
While I am still struggling to divide polygons into same sizes in ArcGIS (we are using ArcView 3.0 scripts now which work fine), I now have an even much more complicated problem:
I would like to ...
3
votes
1answer
102 views
Enter 4 Coordinates and get a Polygon QGIS
Is it possible to enter 4 Coordinates for getting a Polygon.
I have to Clip lots of exact rectangles and i was just wondering wether you know a plugin.
Thanks a lot
danke!
Alex
2
votes
1answer
346 views
How to take polygon centroid in Postgis
I have table with column name,Latitude and Longitude.I want to update this with polygon name and its centroid latitude longitude.I know there is a function in postgis st_centroid(geometry). But I want ...
5
votes
4answers
202 views
How to avoid holes in polygons from lines?
I am trying to convert a dataset of lines that contains the coast of New Zealand into a big polygon.
However using the vector -> geometry tools -> lines to polygon command in Quantum GIS results in a ...
3
votes
3answers
320 views
Finding centrelines from polygons?
I was wondering if there is a way to create centre lines from polygons in QGIS? I have a polygon layer, but ideally need the centrelines as a separate file.
Thanks,
Alan
2
votes
1answer
477 views
Create polygon based on the spatial extent in arcgis
Is there anyway that I can input
1) The Coordinates System (projected is OK)
2) The boundingbox
and create a rectangle polygon based on these?
-2
votes
1answer
171 views
Postgis error on select all intersetcs of a polygon [closed]
i can get all polygon on intersects this:-7.9245860488441 -37.122384500713,-7.9245860488441 -37.11904223938,-7.9233955716106 -37.1187601948
SELECT *
FROM propriedades
WHERE ST_Intersects(
...
1
vote
3answers
189 views
How to create a generalized polygon layer from a raster?
I have a tiff file where I have extracted vegetation in a height interval from LIDAR. At the moment the picture is kind of blurry with no data cells between vegetated cells. I would like to create a ...
3
votes
1answer
294 views
How can I get my Qgis area calculations in metres rather than degrees? My shapefiles are projected using WGS 1984 UTM fuseau 35 Sud
I am using Qgis 1.7.4 to calculate the area of polygons. My shapefiles have been projected using the coordinate system WGS 1984 UTM fuseau 35 Sud, but my area calculations are still displayed in ...
5
votes
1answer
124 views
How can I increase performance on inserting features with polygon geometry?
I have a problem when inserting features with polygon feature class in FGDB. This is my code:
... initialising some fields (does not affect performance)
m_featureBuffer.Shape = ...
0
votes
0answers
249 views
How to do a spatial join if QGIS 1.8 keeps crashing?
I am trying to perform a simple spatial join (adding polygon data to points) in QGIS 1.8:
target vector: points
join vector: polygons
take attributes of first located feature
keep all records
...
