Questions tagged [overlay]

A spatial operation in which two or more maps or layers registered to a common coordinate system are superimposed, either digitally or on a transparent material, for the purpose of showing the relationships between features that occupy the same geographic space.

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4
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2answers
5k views

Load layers only when zoom level is reached

I'm trying to load different layers based on the user zoom level with OpenLayers. I've seen some similar questions in here, but they load the layer and then hide/show it based on the zoom level. I ...
3
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4answers
3k views

Produce a list of polygons that a line crosses

I have a polyline feature class and a polygon feature class. What I want to do is add a field to the lines that lists all polygons that touch the line. This is effectively performing a select-by-...
3
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2answers
1k views

How to calculate the shared area between a raster and a shapefile in ArcGIS 10?

I have a raster file with 5 classifications developed from habitat modelling algorithms. I'd like to know how much of 2 classes of the raster is covered by the network of protected areas (Shapefile). ...
3
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2answers
2k views

How can I move diagrams?

Is there a way to locate diagrams and move them wherever you want in QGIS 1.7.4/ 1.8.0? I created a pie chart under the tab "diagram". I can mark those diagrams with a green box and move them via the ...
3
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1answer
2k views

OpenLayers doesn't show an overlay with a different SRS than the base layer

I need to add an overlay layer that uses EPSG:4326 to a map with a base layer that uses EPSG:32628. Every time I add the overlay OpenLayers automatically switches the SRS param of the overlay to EPSG:...
3
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2answers
2k views

Clip depth contour with spatial polygon

I need to somehow combine my Spatialpolygons with my depth contour, but not sure how do to so. Maybe create a SpatialPolygonsDataframe? This is what I've done so far: > class(subarea0) #This is ...
3
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3answers
444 views

Display millions of points in the browser

I have a web application which will track he movement of user, and save the history location to database. And user may want to see his/her movement trace over a period of time, we have to display ...
3
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3answers
17k views

Can OpenStreetMap be used as a WMS service in MapServer?

I want to produce a png image that uses OpenStreetMap data and has a vector overlaid on the base data. I am able to produce the vector overlay from within Mapserver, but I have difficulty ...
3
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1answer
817 views

ST_RELATE - Intersect ignore shared boundary

Using postgis I am trying to find polygons that intersect, ignoring polygons that only have a shared boundary (edge). ST_Relate(g1, g2, 'T********') is a standard intersection. ST_Relate(g1, g2, 'TF*...
3
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1answer
2k views

Loop to check multiple polygons overlap in r

I have a set of polygons (available here: http://ulozto.cz/x39ELbFt/polygons-zip) created in QGis and processed in R. I would like to know if they are overlapping or not, and if yes, where is the ...
3
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2answers
661 views

calculate coastline at risk

I have an idea of what I want to do but I don't know yet what tools will bring me there. I have administrative boundaries in one layer and coastline in another layer. The coastline is categorized in ...
3
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1answer
895 views

polygon map overlay algorithm

There are many algorithms for binary map overlay operation in vector data format which take two layers of map and produce resultant layer i.e overlaid layer as output. I am wondering whether there are ...
3
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1answer
373 views

Map matching of one sided road data to two sided road data

we use BOS method (Goodchild and Hunter,1997) for checking the positional accuracy of test map dataset by buffering around the reference dataset and then check for percentage coverage of test dataset ...
3
votes
1answer
89 views

Polygon made by colour difference

I need to analyze differences (historical) in coverage of some species (seagrass Posidonia). Although its a marine species, subject area is very shallow and even from common satellite and aerial ...
3
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1answer
211 views

PostGIS function ST_SymDifference between two segment groups produces unexpected results

I try to calculate the symmetric difference for a set of segment groups A and B with precision of 1E-5 (ST_SnapedToGrid(geom,1E-5). I've formulated the an ideal test case for a H based shape segment ...
3
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1answer
857 views

Overlay Analysis in QGIS (or Preferably Python)

I would like to perform an overlay analysis in Python or QGIS to output a list of each shapefile that falls within certain boundaries. I have unsuccessfully tried to use the Spatial Join, Intersect, ...
3
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1answer
3k views

How to overlay a county boundary on a raster file?

I want to overlay California county boundary top of raster layer. Here is is my code: data(coastsCoarse) data(countriesLow) library(gtools) library(maps) library(maptools) library(sp) # Raster ...
3
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2answers
506 views

Get tile layer intensity at given zoom and longitude/latitude (Leaflet)

I can display a tile layer as an overlay in Leaflet via an url of the form path/to/my/tile/layer/{z}/{x}/{y}.png : my_overlay = L.tileLayer('http://path/to/my/tile/layer/{z}/{x}/{y}.png', { maxZoom: ...
3
votes
1answer
152 views

Strange banding in output raster after weighted overlay

I am trying to conduct a weighted overlay. I have two rasters, one is a continuous slope raster that I reclassified to have 6 classes (8-bit signed integer), and one is an elevation raster that I also ...
3
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1answer
981 views

Removing land area from marine region polygons using R

In my pursuit to merge multiple polygons for the purpose of calculating the surface area of marine species distributions, using shapefiles from Marineregions, I am now trying to remove potential land ...
3
votes
1answer
2k 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
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1answer
1k views

Why does my WMS layer overlap the Google Maps v3 logo?

I'm using Google Maps v3 as a base layer and on top of that I create an overlay pointing to my WMS (streets and avenues). A few months ago all works fine, my WMS layer was not overlapping the Google ...
3
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1answer
194 views

Calculating the time taken to complete the overlay display in map?

Currently, I am able to calculate the server response time by logging the difference of current date to initialize the map with the time when layers is added. But this gives me server response time. ...
3
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1answer
187 views

R Overlay points and polygons with a certain degree of tolerance

Also asked here Using R, I would like to overlay some spatial points and polygons in order to assign to the points some attributes of the geographic regions I have taken into consideration. What I ...
3
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1answer
112 views

Define precision in geometric predicate methods in PyQGIS

It is possible to define precision for geometric predicate methods, such as: intersects (), contains (), equals (), touches (), overlaps (), within (), crosses() For example, I'd like to set the ...
3
votes
1answer
566 views

Determining which polygon(s) each point lies in using QGIS?

I am using QGIS software. I have shapefile layer of points and a shapefile layer of polygons(many of them overlapping). I need to determine which polygon(s) each point lies in. I tried "Join ...
3
votes
1answer
86 views

How do I edit multiple features at one time?

In my case, there are about 30 overlaid features. How do I select all and edit them at one time? I want to reshape the features, mainly using the node tool to reshape a straight line into a (fake) ...
3
votes
1answer
4k views

UK region overlay on map

I'm hoping to overlay UK regions (East Midlands, Wales, London etc) on a Google Map. Ideally the regions could be coloured, opaque and have some form of label. There is no hover / interaction ...
3
votes
1answer
1k views

Area overlay of census on Zip Code

I have census block data polygons. I want to overlay them over Zip Codes (larger polygons) in order to estimate the population in the Zip Codes. Or overlay buffers around toxic waste sites over census ...
3
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0answers
130 views

Shaded KML overlays on OSM tiles in QGIS?

This seems simple - but the solution is escaping me. I have a series of dynamically generated KML files describing simple, shaded polygons, with each polygon having a slightly different (externally ...
3
votes
0answers
759 views

Raster Over Layer in Leaflet from GeoServer

I want to add a raster over layer onto the base layer and the raster layer is published by a Geoserver WMS. I set the raster layer's geographic coordinate system as the same as the cloudmate tiles. ...
2
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2answers
7k views

Creating a new raster layer based on mean of other raster layers, ignoring NA values in R

I am trying to create a new raster layer that is made up of the mean values from 7 other raster layers. I get results using overlay function mean: mean <- overlay(2000, 2001, 2002, 2003, 2004, ...
2
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2answers
380 views

Identify parcels that have two types of land use

I have two polygon layers in a geodatabase. One layer is land parcels. The other layer is land use. I want to identify the six largest parcels that contain both "upland forests" and "wetlands" (i.e. ...
2
votes
2answers
685 views

Averaging overlapping rasters with gdal

I am working on creating a class which will merge several georeferenced rasters into one using different strategies, essentially taking average, max, min where the images are overlapping. So far I've ...
2
votes
1answer
4k views

Apportioning Neighborhood Information to Census Tracts using ArcGIS Desktop?

I have a shapefile of census tracts and another shapefile of "neighborhoods" with values that I need to have joined to the census tracts. I know I need to apportion the area of the neighborhood ...
2
votes
3answers
2k views

How to find most common classification within buffers?

I have a point shapefile that identifies the location of incinerators in England and an output area classification shapefile. I have created a buffer for all the points in the shapefile because i ...
2
votes
2answers
4k views

Tile server overlay in Google Earth?

I have recently become aware of a number of tile-server map sources and I would like to use these as overlays in Google Earth. Is there a way to do this directly that does not involve pre-downloading ...
2
votes
2answers
2k views

Calc vs. Overlay for speeding up band math in R 'raster' package?

Regarding Speeding up band math in R 'raster' package, would it be the same to use overlay to calculate NDVI instead of calc and, if that is not the case, then what is the hidden advantage of ...
2
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2answers
11k views

How do I overlay a KML on leaflet 0.4.4

I am using Leaflet 0.4.4, I have a KML I would like to overlay on the map, how do I go about doing this? Edit: I am already aware of https://github.com/CloudMade/Leaflet/issues/14, which directs ...
2
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2answers
75 views

Raster Calculation with 2 Raster Layers [closed]

I am attempting to create a new raster layer based on the values of one raster layer using a formula that is conditional based on the values in another layer. Two source layers: > ndvi class ...
2
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2answers
660 views

Finding overlay percentage between two polygon shapefiles

I have two layers that I am currently working with: 1. Parcels/property boundaries and 2. Wetlands I am trying to determine the parcels that have 0 wetlands and then for the parcels that do have ...
2
votes
1answer
882 views

Convert geohash to shape/kml

I have a requirement where I need to convert a set of Geohash to KML files such that they can be used as areas to plot data by overlaying on map. Is anyone aware of an open resource which can help ...
2
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2answers
160 views

Why such a large difference between overlapping LiDAR DEM values?

Background: Using Arc Desktop 10.5.1, I have been tasked with mosaicking two adjacent LiDAR rasters (I'll call them A and B). They were flown, processed and supplied under contract by different ...
2
votes
1answer
293 views

Determine the range of values in one raster associated with certain values in another raster

I have two rasters, one with thematic data, and the other with continuous data (floats). I am trying to calculate/determine the the range of float values associated with the different classes in my ...
2
votes
2answers
118 views

Selection on Overlapping Polygons

I have converted a CAD file to GIS format using GIS (from .dgn to .shp)... In one layer I have polygons in which a smaller one is on top of the larger polygon. I can see both polygons however when I ...
2
votes
2answers
107 views

How to overlay subset of one data set onto another

I have two data sets: one for Thurston County, Washington and one for all of Washington state. I created a map of hydrology features in Thurston County, and now I want to take the data from the ...
2
votes
2answers
684 views

count features in polygon shapefile A that fall within each feature of polygon shapefile B

I have two polygon shapefiles, each of which contain multiple (possibly overlapping) polygons. Is there some way, using GRASS, to calculate the number of polygons belonging to shapefile A that fall ...
2
votes
2answers
1k views

QGIS layers no longer overlay when Enable 'on the fly' CRS transformation is on

My QGIS project has two layers - one retrieved from GADM (administrative boundaries of Guinea Bissau) and another one of the villages collected in the field using GPS Decimal Degrees - D.ddddd. If I ...
2
votes
1answer
453 views

Rasters in R - merge taking mean, excluding NAs. Overlay and Mosaic both giving funny results

I have a series of raster images, all derived from LandSat data, which give pixels a value of 1 if they are predicted to contain water, 0 otherwise. Many of these images are from the LandSat 7 ETM+ ...
2
votes
1answer
94 views

Calculating areas by overlay analysis of two tables with several information

I have to calculate the areas (m2) of the blue, green and yellow polygons within different vegetationtypes (also polygons - the table is overlaying the colormap). I have to calculate how large areas ...