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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11
votes
4answers
1k 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 ...
10
votes
2answers
176 views

Are “gridded data” and “raster data” the same thing?

I'm working on a project that will involve both "raster data" (aerial imagery and DEMs) and "gridded data" which I understand to be other kinds of numerical measurements taken at grid points, and ...
10
votes
2answers
2k 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 ...
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 ...
8
votes
3answers
2k 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 ...
8
votes
2answers
175 views
+250

A global, grid-like projection for creating heatmaps

I'm putting together an application where I need to create a vector grid which will be used to store and display a heatmap. It has the following requirements: Can cover the entire planet. The vast ...
8
votes
1answer
168 views

Most Effective Format to Manage Aerial Photography for Viewing Only

What is the most effective format to manage aerial photography for viewing in ArcGIS? I manage several datasets of Aerial Photography at a few different companies. I have backups of the original ...
8
votes
3answers
1k 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 ...
7
votes
3answers
915 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 ...
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 ...
7
votes
1answer
967 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
6answers
690 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
3answers
723 views

Overlay a spatial polygon with a grid and check in which grid element specific coordinates are located

How can one use R to split a shape file in 200 meter squares/sub-polygons, plot this grid (incl. ID numbers for each square) over the original map below, and evaluate in which square specific ...
6
votes
1answer
2k 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?
6
votes
2answers
4k 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
3answers
951 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
915 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
391 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
1answer
209 views

Terminology problem - Raster vs Grid vs Lattice

I have a question about GIS terminology - what is the difference between grid and raster and grid and lattice - in theory?? I thought, that raster is regular network and value is in the cell and the ...
5
votes
1answer
257 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 ...
5
votes
3answers
360 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 ...
5
votes
4answers
202 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
466 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 ...
5
votes
1answer
134 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, ...
5
votes
1answer
539 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
1answer
132 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
748 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
1answer
439 views

How to specify coordinate reference system (CRS) for scalebar that is different to project CRS?

Is it possible to specify a coordinate reference system (CRS) for the scalebar that is different to the project CRS? For example, my project CRS uses geographic coordinates (lat/long), the reason ...
4
votes
1answer
328 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
85 views

Rasters stored in folder: Is there a limit at 5,000?

I have a python script that creates batches of ~6,000 cost distance rasters. These rasters are intermediate data that will be summarized in another process. Output is stored in plain old folders. ...
4
votes
2answers
1k views

How to read this GRIB data [closed]

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
3k 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
2answers
2k 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
1k views

Conversion of GRIB and NetCDF to my database

. I have downloaded "High Resolution Initial Conditions" climate forecast data for one day, it was in extension .tar.gz so I extracted it in my local directory and I get the files like in the ...
3
votes
1answer
610 views

Why does QGIS hang when I try to create a vector grid?

I am working in open layers plugin.i need to project the satellite data with respect to vector data shape file i am having .for that Andre Joost suggested to create vector grid with vector data ...
3
votes
2answers
439 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
2answers
937 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
42 views

How to model a geodesic grid in PostGIS?

Abstract I've decided to use PostGIS for a hobby game project. It requires a lot of units allocated on the surface of a planet. I'd like to model not only the units (simple points), but also their ...
3
votes
2answers
344 views

Creating DSM and DTM from a LAS using a freeware solution

Is it possible to export a surface and terrain model files from an aerial, LiDAR point cloud (LAS) set? I am using SAGA GIS for very basic operations, but I couldn't find this option (and I have a ...
3
votes
1answer
80 views

How to tell the size of grid cells created by the vector grid tool?

Im working with qgis 1.8.0 and Im making a vector grid on a map. Does someone know how big are the squares if the grid settings look like in the picture? Thanks for your time!
3
votes
1answer
271 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
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?
3
votes
1answer
216 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
2answers
393 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 ...
3
votes
1answer
160 views

GIS beginner - interpolating contour lines from TIN-model vs. Grid in ArcGIS

I am a complete beginner in GIS and taking a class right now, and we are doing some assignments in ArcGIS - ArcMap. In one of them we were given a shapefile with heightpoints. These had been manually ...
3
votes
1answer
212 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
74 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
137 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
21 views

How to calculate 90% confidence interval in a raster stack

I have a stack of grid files (23) in ASC format from a MODIS sensor and I need to calculate a 90% confidence interval, mean, min, etc, for each one in R, how can I do that? specially the interval. ...
3
votes
1answer
154 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 ...