Use the `raster` tag for questions about raster datasets. A "grid" is a regular partition of a spatial domain into congruent nonoverlapping pieces or a set of lines forming a grid-like pattern (aka "graticule").
10
votes
3answers
505 views
How can I generate irregular grid containing minimum n points?
Given a large (~ 1 million) sample of unevenly distributed points - is it possible to generate irregular grid (in size, but could also be irregular in shape if that is possible?) that will contain ...
9
votes
3answers
2k views
Divide a complex shape file into a grid
I have a decently detailed shapefile with polygon/multipolygon features (the file is about 500mb). It's actually a shapefile of the entire world, with the features representing coastlines. I need to ...
7
votes
2answers
269 views
Aggregating points to grid using R
I have a question with regard to spatial aggregation in R.
What I am trying to do is aggregate a point dataset to a grid.
I am unsure however how to do this as I have little experience with this sort ...
7
votes
3answers
413 views
Creating regularly spaced, defined # of points within polygon in QGIS
I used the research tool "Regular Points" to produce a certain number of points within a polygon, but it forms a rectangular grid of points rather than only within the shape of the polygon. Since I ...
6
votes
6answers
533 views
How can I convert a DEM into areas of “flatness”, with an arbitrary fill/cut to area ratio?
I want to find areas of relative "flatness" in a DEM.
How can I find flat areas? I want to find a neighbourhood of contiguous cells that have an elevation variance that is within a certain ...
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 ...
6
votes
1answer
1k views
How to convert point data into a gridded dataframe for histogram analysis?
I am very new at using GIS data and only modestly experienced with R. I've been reading about how to analyze spatial data using the spatial-analyst.net PDF book, so I'm not completely lost, but I ...
6
votes
3answers
588 views
Find a proper path between two nodes in a grid
This question is about finding a proper path (route) between two nodes (P,Q) in a grid (i.e., graph, network, ...). In our concept, we define a path proper (nice) if it is the most similar* to the ...
6
votes
1answer
592 views
Coordinate grid display on a rotated map
I have a series of maps that require me to rotate my data frame within my layout screen (north "rarely" points up in these maps). I ONLY want to show east coordinates on the top/bottom and ONLY north ...
6
votes
1answer
649 views
ArcGIS 10: Adjust custom grid intervals based on map scale?
I am preparing a pmf which includes a custom grid overlay. To clarify: a custom grid overlay is marginalia, not a feature class with geometry (so a scale dependecy inside a layer won't work). The ...
5
votes
2answers
272 views
Optimum grid/pixel size for interpolating rainfall and temperature
I have a set monthly rainfall and temperature data within an approximately 100 x 100 km study area. The sampling points are unevenly distributed within the study area. Based on a paper by Janis et. ...
5
votes
3answers
1k views
Ordnance Survey grids - download or generate?
Does anyone know a source from which to download vector UK Ordnance Survey grids at varying resolutions? Or failing that, a tool that can create an OS grid at a specified resolution? There are plenty ...
5
votes
4answers
160 views
What to call these types of grids?
In a GIS application I'm developing there's an option to show two types of grids. First is a standard lat/lon grid. Second is a crosshair with marks and distances in four directions away from the ...
5
votes
1answer
98 views
How to convert PostGis Table (Grid data) to Continuous field using Qgis?
I'd like to transform my Gridded Layer (generated form a PostGIS table of points) to a continuous and colored layer. How could I do this with Qgis or any other program?
Many thanks and best regards,
...
4
votes
1answer
83 views
How do I split a vector layer into separate grid layers?
I need to split a vector layer into 1km x 1km squares so I can carry out some calculations for these individual areas. Is there a feature to do this?
4
votes
1answer
279 views
How to create a 500m Regular Grid for KML input area?
I am hoping to create a point grid over the city of Edmonton. My workflow is:
Import a KML of Edmonton neighborhoods from here
Save the layer as a SHP
Delete the layer and load the SHP
Define the ...
4
votes
3answers
259 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 ...
4
votes
1answer
99 views
Help with grid creation in QGIS
I have 235 raster tile 20km x 20km. I need to create a grid to overlay across them...ie the grid itself will be 20km x 20km, with the lines of the grid on the boundaries of the tiles.
I am assuming ...
4
votes
1answer
214 views
Sub-dividing a polygon into smaller polygons
In OpenStreetMap data, some large areas are tagged with a residential=yes tag. Actually within this large polygon there are multiple smaller (rectangular) houses (which are actually not drawn as yet). ...
4
votes
1answer
152 views
Converting polygon values to a vector grid using PostGIS
What is the best way of converting a value from irregularly shaped poylgons to a polygon grid using PostGIS? I have a set of polygons that look like this:
and I would like to overlay a grid on ...
4
votes
1answer
221 views
How to emulate a specific vector grid in QGIS?
I would like to analyze data included in a pdf file. The file contains information on characteristics of 16km grid cells for a specific study area. The file also includes a map displaying the grid. I ...
4
votes
2answers
814 views
How to read this GRIB data
on this open FTP server (ftp://ftpdatos.aemet.es/modelos_numericos/hirlam005_peninsula/) you can find HIRLAM models from the Spanish meteorological service.
The documentation in the LEEME files (in ...
3
votes
4answers
1k views
How to create a grid whose vertex coordinates are shown on an attribute table in Arcmap?
I have a specific area to study. Before starting on my field work, I have to create a 310m X 310m grid of the area. Later on I have to get the coordinates of each point of the grid in an attribute ...
3
votes
1answer
314 views
Grid and Graticule in QGIS Print Composer
Is there any other option to display DMS grid and graticule in QGIS Print Composer, since there is no plugins available yet?
3
votes
2answers
706 views
How to convert GRIB-1 to GRIB-2?
I need to get data for my database from some GRIB files (binary), I downloaded wgrib2, which can export GRIB-2 files to .csv and csv is very suitable for me, but some GRIB files are GRIB-1, so I used ...
3
votes
2answers
377 views
From point to Grid of polygones or polylines
Is it possible to reconstruct a grid of polygones or polylines from the centroids?
I am looking for a arcGIS tool or script that will allow me to reconstruct a grid of polygons or polylines from ...
3
votes
1answer
96 views
Find which grid cells contain a point
I have a dataframe with x,y coordinates. I've sampled 10 x,y coordinates from my dataframe:
y <-c(24.637032,21.569813,21.687,19.677183,24.72438,21.433136,24.637032,22.21065,21.443762,25.273882)
x ...
3
votes
1answer
225 views
How to display DMS in QGIS print composer?
Can we display degrees, minutes, seconds in QGIS Print Composer window instead of decimal degrees? Is there any plugins available for that?
Thank you very much.
3
votes
1answer
253 views
Different coordinate system for map project and scalebar?
Is it possible to specify a coordinate reference system (CRS) for the scalebar that is different to the project CRS?
Example: my project CRS uses geographic coordinates (lat/long), the reason being ...
3
votes
1answer
587 views
How can I add a grid (from projection MTM8) on my layers
I need to add a grid on a map I created with my own layers and GPS data. How can i do this? I know how to do it in Arcgis, but not in QuantumGIS. Can you help me?
3
votes
1answer
132 views
Polyline “breakage” calculation in MapInfo?
I am a novice MapInfo user, with a basic to moderate knowledge of queries and SQL. My work entails doing risk assessments for shipping traffic based on AIS-tracks (radio-based vessel information ...
3
votes
1answer
57 views
How to modify height model values outside of road network
I have a height model of a quite big area saved in Esri ASCII grid files and a road network of this same area in a shapefile. I'd like to convert every height model value outside the road network to ...
3
votes
1answer
141 views
Dividing a geographic region
I have a certain geographic region defined by the bottom left and top right coordinates. How can I divide this region into areas of 20x20km. I mean in practial the shape of the earth is not flat it's ...
3
votes
1answer
100 views
Method to compute and visualize the closest set of facilities from OSM data
I want to use OSM to extract a set of facilities e.g. school, park, hospital inside a given region.
from that, transform the area in grid and for each cell in a grid compute its score mixing the ...
3
votes
0answers
90 views
How to view Esri GRID format file in wxpython file browse window? [closed]
I'm trying to browse for all kinds of vector and raster data using a filebrowsebutton.
The problem is I don't know how to let the browse window see the Esri GRID files (which contains a folder and a ...
2
votes
4answers
297 views
ArcInfo Grid ASCII to ESRI Shapefile conversion
I have an ArcGIS grid ascii file (Ramankutty Cropland at 5 minute resolution) that begins as follows:
ncols 4320
nrows 2160
xllcorner -180
yllcorner -90
cellsize ...
2
votes
1answer
463 views
Convert X Y Pixels to Easting Northing
Hopefully someone can help.
I'm trying to find out what the formula would be to convert the X, Y of an image to the Easting and Northing coordinates.
I've downloaded some of the raster maps from OS ...
2
votes
3answers
168 views
Looking for a fine U.S. Latitude and Longitude grid (0.25, 0.5 degree)
There is a global latitude and longitude grid data available at 1 degree resolution and higher (http://www.arcgis.com/home/item.html?id=f11bcdc5d484400fa926dcce68de3df7). Is anyone aware of a finer ...
2
votes
1answer
98 views
How extract data from a SNODAS file
I'm trying to extract data from a raster file from "Snow Data Assimilation System (SNODAS)" and convert it to a MMQGIS (plugin) grid layer (Hexagon) with QGIS.
This raster file stores the snow depth ...
2
votes
2answers
2k views
Converting xyz batch to ESRI grid format using XYZ2GRID 2.1 - batch problems
I am trying to use Min-Lang Huang's XYZ2GRID2.1-Batch program downloaded from ArcScripts and I keep getting the error
C:\users\public...........xyz Error-Object required
Does anyone know what the ...
2
votes
1answer
89 views
filter / generalize elevation points on the basis of some conditions
I wanted to generalize many elevation points in a rectangular area (about 700 square km). I need to take about 3 points for square km. These points must satisfy some conditions:
One of these ...
2
votes
1answer
68 views
How to flip X and Y coordinates of a grid by GDAL
I have a grid, which has flipped X and Y coordinates (X is represented by Y values and Y is represented by X values). This results in grid being positioned in completely wrong place.
How can I flip ...
2
votes
2answers
87 views
gridlines are on top of some text boxes but below others, how do I make it so that the text boxes are above the gridlines in all cases
I am working with a map and instead of using the labels feature I chose to use text boxes because the labels were not where I wanted them to be. I set up all the text boxes and then added gridlines ...
2
votes
1answer
237 views
How to export vector features to grid using proxy and WFS protocol?
I am trying to export vector features (current view) as a grid, something like: http://workshops.opengeo.org/geoext/wfs/grid.html
so far layer features are not being retrieved.. I got empty grid in ...
2
votes
2answers
249 views
TIFF, Grid, FGDB Grid, etc. - what performs better in ArcScene animation?
I am creating a flyover animation in ArcScene and I would like my surface raster to be rendered in full resolution (an exported function raster dataset - a blend of shaded relief and high resolution ...
2
votes
0answers
67 views
draw lines with an angle inside a rectangle in python
I am trying to make a plugin for Qgis with python. I have the four corner coordinates for a rectangle. I want to give the user the inputs, line space and angle (0 -180 degrees).
With these inputs, I ...
2
votes
1answer
141 views
Create a square grid polygon shapefile with python
i have the following coordinates
minx,maxx,miny,maxy = 448262.080078, 450360.750122, 6262492.020081, 6262938.950073
i wish to create a square grid of size 1 m using python.
import math
...
2
votes
0answers
76 views
Plot the Shortest Paths in a Grid without any clash at a point of time
The efficient algorithm needs to be done and proved for the best solution for the given problem:
User inputs: (#) Size of the NxN Grid. (N); (#) No. of Paths: Z; (#) Source and Destination ...
2
votes
1answer
191 views
UTM Grid as a Layer with Leaflet
How can I display a UTM Grid as a layer with Leaflet?
Search a way to embed a OpenStreetMap map with Leaflet in a website.
Particularity. I want to display a UTM Grid as a Layer.
In addition, lower ...
1
vote
2answers
217 views
Arcpy (10.0) and centroids/points shapefile
I'm trying to create a point shapefile from a grid index polygon shapefile I created using arcpy. I know this is simple, but could anyone give a few pointers out there. Here is what I've done now:
but ...
