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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8
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2answers
679 views

Computing dominant area in polygon using ArcGIS Desktop?

First, I have a shapefile consisting of square grids and each grid has an ID. Second, I have a shapefile consisting of different zones (with IDs). A grid ID in the first shapefile can contain many ...
2
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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 ...
8
votes
1answer
8k views

OpenLayers WFS vector layer

I'm trying to add a vector layer with a WFS layer and it's not working. Can anyone point a solution? OpenLayers code: var wfs = new OpenLayers.Layer.Vector( "Stavros Features", ...
9
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4answers
17k views

How to reproject base layers in OpenLayers?

I have vector/topo/image tiled maps for some places in North America which were published as ArcGIS Server REST service. These maps (A) are based in EPSG:26912 projection. Now I want to use these as ...
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 ...
17
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6answers
29k views

how to overlay a polygon over SpatialPointsDataFrame and preserving the SPDF data?

I have a SpatialPointsDataFrame with some additional data. I would like to extract those points inside a polygon and at the same time, preserve SPDF object and its corresponding data. So far I've ...
2
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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 ...
14
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1answer
2k views

Method to shade or overlay a raster map to reflect time of day and ambient light

I have a daytime raster of my study area. I have 20+ counters in the study area that count "stuff" with a timestamp. Using PyEphem I determined the type of ambient light for each collected data point. ...
6
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1answer
768 views

overlay county shapefiles for 2 different years

I have county-level shapefile for South Caroline in 1880 and one for 1940. I would like to overlay these two files so that they do the union and indicate the percentage of the land in 1880 that went ...
3
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1answer
949 views

remove land area from marine region polygons

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 ...
8
votes
3answers
2k views

Create interactive map with no server

I have managed to build a great web mapping application using tiles created from GeoWebCache and a custom gridset, but I now need to add an overlay to the base maps. The only interactivity I need is a ...
4
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1answer
2k views

Does OpenLayers supports KML Ground Overlays?

I am not able to display Ground Overlays in a KML file with OpenLayers. Does OpenLayers supports KML Ground Overlays? If not, how would I proceed in writing my own code or plugin for OpenLayers so ...
2
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2answers
5k views

Defining which layer (overlay) is displayed on Leaflet map?

I have 7 layers overlay on a base map, i need to define which layer is selected (active,displayed,shown) on the map. var overlays = { "AL HOUDA Espaces_Verts": alhouda6_layer, "...
4
votes
1answer
2k views

How to select polygons by points in R?

I have a shapefile with polygons and another one with points. I would like to create a new shapefile with those polygons that don't contain any point inside. I tried the function sp::over in R and it ...
3
votes
1answer
195 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 ...
1
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1answer
1k views

Testing point in polygon overlay performance of Intersect, Spatial Join and Near in ArcGIS for Desktop?

In answers and comments to Select points within a polygon and update attributes I think it is being suggested that Spatial Join (Analysis) and/or Near (Analysis) may be faster than Intersect (Analysis)...
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2answers
46 views

Adding information to polygons inside polygon from other polygon in QGIS?

I have two layers in QGIS. The first one contains buildings and the second one contains blocks. Now I want to add the ID of the block to all buildings inside this block. Are there any functions in ...
4
votes
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 ...
8
votes
1answer
3k views

Generating grid shapefile in R?

I have the following shapefile of a 10x10 degree latitude/longitude grid that I created in QGIS. I can read it into R using the rgdal package. Grid<-readOGR(".","GridShapeFile") It has the ...
4
votes
2answers
3k views

R: Overlay using functions containing if/else statements

I have two rasters, x and y, and I'd like to do calculations with them using the overlay function. For example, MyFun <- function(x, y) x * y res <- overlay(x, y, fun = MyFun) This seems to ...
4
votes
2answers
921 views

Overlaying a polyshape to faceted maps in R with ggplot?

I have managed to create a faceted map from my data following the approach proposed here http://spatial.ly/2013/12/introduction-spatial-data-ggplot2/ with the following code: ggplot(data = plot.data,...
3
votes
3answers
428 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
votes
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
votes
1answer
837 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, ...
1
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3answers
2k views

“Identity” overlay in QGIS?

I have two polygon layers I'd like to overlay using QGIS or another open source tool. What I want as output is a polygon layer with the extent of one polygon, but with each polygon in that layer ...
0
votes
2answers
5k views

Calculating proportional data for polygon by taking attributes from other polygon

I have a features class which has polygons in it. I also have a Block group level data for demographic variables like population. Now when I overlay the polygon on the block group level data to find ...
10
votes
2answers
4k views

How to rasterize SpatialPolygons in R?

I'm trying to extract the bathymetry values of my area of interest from a world bathymetry raster layer using the 'rasterize' function in the {sp} package. *Edits: I found the 'extract' function ...
5
votes
2answers
1k views

Calculating edge length of polygon within overlapping polygon using ArcGIS Desktop?

I have a layer of wetland polygons and a layer of lakes. I basically want to find the total length of lake shoreline contained within each wetland and add these values as an attribute of the wetlands. ...
5
votes
7answers
2k views

Problem with Swiss coordinate system overlay in WMS

I have administrative boundaries data for communities in Switzerland from SwissTopo. Original data came in shape files with 'Bessel 1841 Hotine Oblique Mercator Azimuth Natural Origin' projection. ...
4
votes
3answers
687 views

Is the Intersection Operation Commutative?

In map overlay, is intersection of map layers a commutative operation ie layer_A intersection layer_B = layer_B intersection layer_A? If layer A is a square and layer B is a triangle. In this case, (A ...
3
votes
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 ...
2
votes
1answer
264 views

Spatial Join if more than 50% of join feature overlay target feature?

My ModelBuilder in ArcMap 10.3 includes 2 Shapefiles: Buildings footprint (polygons). Red shapes (polygons) which includes information for each building. The task is creating new layer that contains ...
2
votes
1answer
1k views

Is it possible to intersect multiple polygon shapefiles to identify areas where two or more layers overlap?

I have 19 polygon shapefile layers, with some occasionally overlapping with one another. As a final output, I would like a shapefile that includes only the overlapping areas between 2 or more of these ...
1
vote
1answer
761 views

Calculating coverage of vector polygon over other polygons?

I have a shapefile file that contains a LiDAR footprint and I'm trying to figure out how much a county is covered by the LiDAR footprint. Two separate shapefiles. The attribute table for the county ...
1
vote
0answers
78 views

PyQGIS overlaying raster image on vector map correctly?

I have some code written in Python using PyQGIS where I am trying to overlay a raster image gridded with coordinates on to a vector shapefile map with the same coordinates. However, when overlaying ...
1
vote
3answers
167 views

Spaghetti, meatballs, and the one-to-many problem

I am trying to use the Spaghetti and Meatballs overlay technique to create a fire history layer from Cal Fire FRAP's fire perimeter data. I am following the technique Dale Honeycutt describes in his ...
1
vote
1answer
3k views

Compare two rasters with raster overlay and replace cell value with variable

I want to compare 2 rasters and when there is a change from 2 to 1 create a new raster that replaces the cell where the change has been detected with the change variable. ## Finds Cells that have ...
1
vote
2answers
3k 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 ...
1
vote
0answers
134 views

Polygon overlay, calculating changes, in QGIS?

I'm trying to create a relationship file between two vintages of census tracts. (in this case, 2010 and 2013.) Reason being to load ACS (American Community Survey) census data and use weighted means ...
1
vote
1answer
973 views

Can't display overlay

I am trying to add a WMS radar overlay to my map but it won't seem to gather it. noaaRdr = new OpenLayers.Layer.WMS("Latest Radar", "http://nowcoast.noaa.gov/wms/com.esri.wms.Esrimap/obs?", { ...
1
vote
1answer
768 views

Kml not overlaying onto Google Map

I created a basic dashboard with MVC 4, visual studio 2012, The dashboard displays a Google map. Here is an image of the dashboard: My intention is to be able to take this Kml file: And successfully ...
1
vote
1answer
362 views

Overlap or intersect two choropleth [closed]

I have two choropleth of the same area but with different concentration data and I need to overlap them. My aim is to highlight the areas of intersection between the points with the highest ...
0
votes
1answer
337 views

Using spatial join in ArcGIS for Desktop?

I have two spatial layers of about the same (not exactly same) spatial extent. Layer#1 has about twice the number of polygons than layer#2 (in thousands). I am trying to calculate values for Field#X ...
0
votes
1answer
2k views

Performing weighted sum overlay analysis in QGIS?

I have weighted raster data converted from polygons with different categories. I have ArcGIS with 3D Analyst extension, unfortunately do not have Spatial Analyst, and I would like to use QGIS to ...
0
votes
1answer
713 views

How to overlap a base map with a png map (format .pgn) on QGIS-Pisa?

How can I overlap a relief base map taken from maps-for-free.com and this png-formated map so that I can get a resulting map with relief of the 1st map and boundaries of the 2nd map ?? I'm a ...