Refers primarily to graticules and questions about drawing or constructing them. Use the `raster` tag for questions about grid-based datasets.

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10
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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 ...
8
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 ...
8
votes
3answers
2k 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
1answer
1k 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
739 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
5k 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
1k 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
1k 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
446 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
304 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
391 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
1answer
524 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
152 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
852 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
349 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). ...
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
2answers
1k 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
101 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
337 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
259 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
437 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
237 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
76 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

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
117 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
1answer
1k views

How to create a grid constrained within a polygon in QGIS?

In QGIS I have created an irregularly shaped polygon. I can create a grid based on the maximum extents of the polygon via Vector>Research Tools>Vector Grid. However, what if I need the grid to ...
2
votes
1answer
2k 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
663 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
182 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
147 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
262 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
1answer
555 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
0answers
41 views

simple raster format to use in Web applications?

I'm building a Web application in which users create and edit very coarse raster data. They're assigning values to cells in a georeferenced grid. Right now I'm storing the values in a multidimensional ...
2
votes
0answers
137 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 ...
1
vote
3answers
2k views

how to create grid to divide large map into smaller sections

This seems like it should be easy but I just can't find anything online that tells me how to do it. I have a map of small remnants of forest along creeks for an entire county in California. I need ...
1
vote
2answers
537 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 ...
1
vote
2answers
106 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 ...
1
vote
1answer
742 views

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

For example, the city of Rotterdam represented as a hexagonal grid.
1
vote
2answers
122 views

AML routines and python

I´m trying to use some AML files in ArcMap 10, but I have noticed that this option is not available for this version. Does anyone know or tried to "translate" the aml sequences to another language ...
1
vote
1answer
116 views

Dividing map into features (whole squares)

I'm using QGIS 1.8.0. I divided a map of a state with its municipalities into many features using a GRID (small squares), but instead of creating one ID per feature (one ID per square), it creates one ...
1
vote
2answers
409 views

Openlayers Plugin, Project CRS and Grids in Composer

Apologies in advance for the potential for this to be a duplicate question, I've had a good look, and I can't see a solution thatI understand well enough to help me. I have my project CRS set to a ...
1
vote
1answer
179 views

How can I bring in grid files from Geographix into ArcGIS?

I have a set of grids of subsurface horizons, created from contours, that I have created in Geographix and am having trouble brining them into ArcGIS. Currently when I try to export the grid ...
1
vote
1answer
852 views

How to draw grid cells in QGIS?

I have one ASCII text file with eight columns. The first four provide the x-coordinates (e.g. longitude) of the four corners of a grid cell, while the last four provide the y-coordinates (e.g. ...
1
vote
1answer
1k 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 ...
1
vote
0answers
318 views

Updated: Openlayers Vector Layers with Google Map Base Layer (via Grid): Vectors Stick but can't get correct resolution/projection

Revamping this question instead of opening a new one. Previous issue: vector layers were not "sticking" to the map, so when you would zoom in or out the vector layers would "come out" at you. Note ...
1
vote
0answers
95 views

How to rotate u and v components of wind in rotated gribs?

I have a grib message of a rotated hirlam product. The gribmessage states, that the u and v component contained are relative to the rotated grid. How can I unrotate them?
1
vote
0answers
109 views

Problem using grid with a vector layer

I need to establish a model of maritime pollution and I try to use the grid option to work on ocean sectors. I tried to use my grid on a vector file, .shp, with points. Each point is a maritime ...
1
vote
0answers
123 views

Arcobjects - Properties Grid

Does anybody know a way, in VBA, to change the grid interval? For example: if my layout´s scale is 1:2000, my grid will have 200 meters interval and my layout´s scale is 1:5000, my grid will have 500 ...