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").

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9
votes
2answers
1k 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 ...
2
votes
0answers
118 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 ...
5
votes
1answer
393 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
123 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?
2
votes
2answers
250 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 ...
5
votes
1answer
1k 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?
5
votes
1answer
126 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, ...
1
vote
2answers
407 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 ...
2
votes
1answer
150 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 ...
-1
votes
1answer
446 views

Exporting Grid from R to use it in ArcGIS

i want to export a grid from R into format readable by ArcGIS. how can i do so? jones
1
vote
2answers
86 views

Distribute gridded data to corresponding subbasin boundaries

I have one ArcGIS shapefile of my river basin consisting of many subbasin. Another shapefile showing the location of gridded points over the whole basin (Its latitude and longitude are used as file ...
5
votes
1answer
494 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 ...
0
votes
0answers
91 views

How do I determine programmatically what values to add to the proj4js constructor for a CRS or SRS such that I can iteratively render proper overlays

I think this is primarily a GIS based question as far as for example: var crs = L.CRS.proj4js('EPSG:2154', '+proj=lcc +lat_1=49 +lat_2=44 +lat_0=46.5 +lon_0=3 +x_0=700000 ...
2
votes
1answer
422 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 ...
6
votes
3answers
873 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 ...
3
votes
1answer
195 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
1k 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?
1
vote
0answers
254 views

In ArcGis 10, spatial join of a hot street value to a fishnet cell is counting multiple values for same street segment

So, I am working on a fishnet, so that we can attribute multiple values to points within different cells (i.e., ranking light poles as optimum for traffic cameras based on the number of speeding ...
2
votes
1answer
987 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 ...
4
votes
1answer
627 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 ...
0
votes
2answers
233 views

QGIS regular points around each polygon in a layer (vs ALL polygons)

I have a number of buffered points (some where polygons intersect & are dissolved. I'd like to create regular spaced points grid around EACH polygon -- not ALL polygons. When I do Vector -> ...
6
votes
2answers
3k 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 ...
3
votes
1answer
127 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
2answers
1k 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 ...
0
votes
0answers
932 views

Lat/long grid in QGIS using WGS84 projected layers [duplicate]

I'm using QGIS to project some shapes that are in WGS84 coordinate system. I want to add a grid to the map in the map composer but when I try to do it the degrees don't show up. I have tried to do ...
1
vote
1answer
476 views

How to convert a polygon to a grid of polygons using QGIS?

For example, the city of Rotterdam represented as a hexagonal grid.
3
votes
1answer
72 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 ...
0
votes
1answer
113 views

Why are grid and scalebar measures 1mm too long in a 1:10000 print?

I used qgis 1.8 to compose a map from the WMS-service of the Belgian NGI. I added a scalebar and grid to it. When I measure it by hand, the distance between the longitudelines is 101mm instead of ...
1
vote
1answer
212 views

Grid labels in ArcGIS, overlapping issues

I do have 3 grids made by Grids menu in data frame properties. I do need them to display in certain layout and also to behave accordingly to couple of rules (overlapping issues), so I can automate my ...
11
votes
3answers
897 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 ...
-1
votes
1answer
280 views

how to make grid cells by point data

I have a csv data. the X, and Y columns show bottom left corner of each grid. It is supposed to show as grid square, but it shows points. what is the problem? and is there any way I can make cell ...
0
votes
0answers
110 views

SAGA grid VRT, file how to apply a LUT?

I've created a heap of saga grid files for some hydro survey work. I'm looking at a way to read these into a mapguide raster/grid layer, I'm able to load up the grids using a vrt file, I can't figure ...
3
votes
0answers
106 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 ...
1
vote
2answers
458 views

How to create a valid global polygon grid in PostGIS?

I want to create a grid spawning the whole globe. The grid is used to measure a density value by counting the number of certain spatial objects in each grid cell. To create the grid, I have created ...
8
votes
3answers
959 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 ...
5
votes
2answers
352 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. ...
0
votes
2answers
276 views

How to implement a spatial query on polygon data for a specific point?

I have vector data fed into a database which returns a report at province level upon querying. This is implemented in a web tool. I want to add an extra functionality at point level, where I can ...
3
votes
4answers
2k 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 ...
4
votes
1answer
304 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). ...
1
vote
0answers
314 views

how to get ascii grid from corine land use data?

I'm trying to get ascii grid with land use data (by one parameter - CODE_00). Afterwards I will import it into simulation tool. But I cannot figure out how to convert ascii grid from shapefile. ...
3
votes
1answer
190 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 ...
1
vote
1answer
844 views

Generating Map Tiles for MGRS Grid Graticule

I'm possibly a bit out of my league here, but ready to get my hands dirty. I want to generate map tiles for a MGRS grid graticule similar to http://tiles.mapbox.com/mapbox/map/afghanistan-mgrs. I ...
9
votes
3answers
3k 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 ...
3
votes
2answers
361 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 ...
5
votes
3answers
341 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 ...
3
votes
2answers
739 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 ...
1
vote
1answer
134 views

What are the strengthes and flaws of using grid-cell analysis in GIS with fishnet?

As I mentioned in the title, I'm going to use grid-cell analysis. what are the strengthe and weakness??
7
votes
1answer
2k 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 ...
0
votes
1answer
8k views

How to make a grid with a certain spacing between lines along X and Y axis?

We are doing the research about applying remote sensed data on hydro logical model . After delineating, the river basin from DEM data using Argis9.3, We have to map the remote sensed data derived from ...
7
votes
1answer
855 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 ...