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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2
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2answers
163 views

How to add updated tiles to ArcGIS mosaic

I have several hundred aerial imagery raster tiles (in ecw format) that I have loaded into a mosaic dataset. I would now like to 'replace' or 'overlay' an older aerial imagery layer with this dataset. ...
3
votes
1answer
518 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 ...
1
vote
2answers
570 views

Transforming a Google Maps overlay to fit an Ordnance Survey projection

I am currently in the process of creating a map with some administrative boundaries on it. The base map I am using is an ordnance survey map 1:10000. I downloaded an administrative border as a .kml ...
3
votes
1answer
658 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 ...
0
votes
0answers
164 views

How to hide overlays in Leaflet layerControl if geojson var not found?

i would like to perform a specific task: i have a set of geojson layers, loading features from local files. i have the layercontrol on the map showing available layers to show/hide now, regarding ...
2
votes
1answer
82 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 (8bit signed integer), and one is an elevation raster that I also ...
0
votes
1answer
197 views

Image source of world political map for Google Maps overlay in Android?

I have searched a lot. But I am not able to find some high resolution image of world map showing countries in different colors without label, which I can slice and use to create tile overlay in my ...
1
vote
1answer
130 views

Erasing overlay geometry with in the feature class..!

What is the best practice for erasing overlay geometry? My scenario is: I have a polygon layer with 1000 features. i need to create a tool from model builder that select polygons with user defined ...
0
votes
2answers
123 views

OpenLayers + Geoserver problem with wfs projection

In geoserver i have a layer in EPSG:26191. In OpenLayers i add it on map as WFS: markerLayer = new OpenLayers.Layer.Vector('Markers',{ strategies: [new OpenLayers.Strategy.Fixed()], ...
1
vote
0answers
19 views

How to overlay an NOAA nautical map as a layer in QGIS [duplicate]

I am new to QGIS and am doing some work for a friend. He is hoping to overlay an NOAA nautical map as a layer in QGIS. My only real experience is with ArcGIS. He is looking to do something similar ...
0
votes
0answers
162 views

Overlaying Line (Vector) Layer on Raster Zones?

I will make my best attempt to clearly explain my problem. I am using ArcGIS 10 I have a raster layer with 3 values that make up zones. For the purpose of this example, lets say these zones are ...
1
vote
1answer
975 views

Apportion Neighborhood Information to Census Tracts

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 ...
0
votes
1answer
195 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 ...
0
votes
1answer
598 views

How to overlay a jpg onto a google earth image?

I have produced a model from an online engine , and it is in a google earth picture. I want to georeference the below picture and apply the boundaries here on my google earth image. I'm using QGIS2.2. ...
0
votes
2answers
134 views

Frequency analysis and overlay analysis

Am new to gis and I hope to find help here. I am working on a research that requires that I overlay conditions of drainage systems and quality of healthcare in a coastal state to get areas which have ...
1
vote
1answer
602 views

Merge two maps with OR operation in GRASS

I have two vector maps. The two maps cover the same area but are split up into polygons differently (i.e. if you were to imagine one map placed above the other, the lines defining the polygons would ...
1
vote
0answers
273 views

QGis, how to overlay and correctly position and scale a KML and image onto a Google base map

Being totally new to the entire GIS subject I managed to install and get runnning QGis (2.2.0 on Mac) properly, get my Google Maps showing (I set the the CRS to WPSG:3857) and I also got my KML file ...
4
votes
1answer
921 views

Show markers only at certain zoom levels

I'm building a cycle touring map in leaflet.js, with subjective information overlaid as markers, along the lines of "this is a great road", "this town is quite nice" etc. To avoid information ...
2
votes
1answer
82 views

Combining several rasters before r.surf.contour?

I have been trying to generate an elevation model from contour lines using first v.to.rast.attr and then r.surf.contour. Generally, it works pretty well, execpt for one issue. My data contains a lot ...
1
vote
1answer
130 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
252 views

Weighted Overlay with “nodata” cells

I´m currently conducting a suitability analysis with the weighted overlay function. One relevant criteria is the proximity to highways. If the wind turbine is located up to 300 m away from the ...
1
vote
0answers
231 views

Problem with polygon overlay in raster stats using gdal

I am using the raster_stats module in python to calculate the mean carbon value for different sets of polygons. Here is the code that I am using: africa_sat = ...
1
vote
1answer
81 views

Stamp out and transfer values from one overlayed vector layer to another

I have a vector layer with administrative boundaries and another vector layer with postal code boundaries, which are more precise/smaller entities/objects. I now want to transmit the values of one ...
1
vote
0answers
106 views

Calculating Percent Overlap Between Distribution Maps

Hello there, I am currently trying to calculate the percent overlap (basically the total amount of overlap where these two species come into contact) between Lithobates catesbeiana (first image) ...
1
vote
1answer
78 views

Extract information of a raster overlayed on another raster with a lower resolution directly in python

I have two aligned rasters with the same extent, one has a resolution of 5 meters and the other of 125 meters. I would like to place the 5 meter one over the 125 meter one and assign to these smaller ...
1
vote
1answer
213 views

How to combine Boolean and Fuzzy logic?

So I have a set of 5 Fuzzy Memberships and a polygon feature class, to which I already added a yes/no field. For the final map, I need to combine/overlay all Fuzzy Memberships and the rasterized ...
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 ...
0
votes
1answer
44 views

How to select the identities of a layer present just in one identity of another layer

I'm a student approaching to QGIS 2.0.1-Dufour. My goal is to know how much identities of a layer are present just in one identity of another layer. I tried both with the tools "spatial query" and ...
1
vote
1answer
191 views

QGIS 2.0: move basemap by hand in order to achieve overlaying with a point layer

I am an environmental engineer and the aim of my QGIS 2.0 project is to visualize the results of a sewage water system inspection. In a first step I included the hoppers from a csv file and added a ...
1
vote
2answers
81 views

Historical maps as cylindrical projections

Objective: I want to overlay old, historical maps on top of Google Maps. According to Wikipedia, Google Maps uses a variant of the Mercator projection, a close relative of cylindrical projections. ...
1
vote
0answers
245 views

QGIS plug-in equivalent of ArcGIS's Spatial Analyst Tools -> Overlay/ Weighted Overlay

Specifically I have 12 .bil raster files that show monthly global mean minimum temperature. I file for each month. I want to combine these to create an ANNUAL global mean minimum temperature. In Arc I ...
0
votes
0answers
43 views

Overlapping of two layers in MySQL spacial extensions

I have been into GIS for almost a week now. Right now, I am learning MySQL spacial extensions. I have a question regarding the functions MySQL provides: I have a table that consists of LineString, ...
0
votes
0answers
297 views

How to import AutoCAD .dwg files as overlay on map in Drupal (using OpenLayers)

I am using OpenLayers on my Drupal site. The request is to import AutoCAD .dwg files as an overlay to maps on the site. Is this possible and how? I found the OpenLayers Editor for Drupal, am I on the ...
0
votes
1answer
58 views

Calculate best area with overlaying multiple layers buffer shapes

I am using QGis and I have a set of 20 layers with buffers. I'm interested in where they overlap most and I want to create a single layer that shows which are the places where they overlap most and ...
3
votes
1answer
519 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 ...
2
votes
2answers
159 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. ...
1
vote
2answers
158 views

What is the most efficient method to delete points?

I have a script that takes a point featureclass (FC) through the following workflow: Select points that lie within individual polygons From the selected points within each polygon, randomly subset ...
1
vote
2answers
109 views

Why does my gpx layer go to the wrong spot even if they have the same CRS?

Help! I am a QGIS beginner with a big problem! I am trying to load a gpx file from Garmin into my map. The project CRS is WGS 84, and the incoming data is in CRS WGS 84. When I look at the bottom of ...
0
votes
1answer
891 views

How to calculate proportional data for a 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 ...
8
votes
3answers
935 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 ...
3
votes
1answer
1k views

ArcMap 10.1 Spatial Join: 'Contains' and 'Within' question

I have two polygon datasets: electoral districts and postal code areas. I'm performing a spatial join to see which postal code areas are completely within a district (the area can touch the borders, ...
2
votes
1answer
173 views

Reproject gif.gz raster to WGS84 in QGIS

I am a steep learning curve into QGIS. I have a raster of global fire maps from the modis site: http://lance-modis.eosdis.nasa.gov/imagery/firemaps/firemap.2013221-2013230.8192x4096.gif.gz I would ...
1
vote
0answers
64 views

How to maintain polygon boundary location during overlay in ArcGIS

I am working with ArcGIS Desktop 10.1 (Advanced license). I am trying to overlay two polygon layers (buildings and landuse) via an Update overlay such that all building polygons are retained and the ...
2
votes
0answers
47 views

Layers with the same Geographic Coordinate system don't overlap [duplicate]

I am a GIS newbie. I'm having a problem that, from the looks of things on this website, is a fairly common problem. I have 3 layers, all in the same GCS that do not line up. I have read all the the ...
1
vote
1answer
200 views

kmz mismatch in the Google Maps API v3 and Google Earth

I have some kmz files(exported from ArcMap). They overlay perfect with the base maps of Google Earth, but when it applied to Google Maps API, they mismatch the base maps. Can anyone give me some ...
1
vote
1answer
82 views

Counting and sum by two layers

I´ve got to layers, both polygons. Layer 1 consists of propertiers, where ID is individually names. Layer 2 consists of lakes. The query I want is: Total count of squaremeters of lakes for each ...
1
vote
1answer
86 views

Why are attributes missing in overlay tab QGIS 1.8.0?

I want to add a diagram overlay onto a shapefile layer. When I look at the attribute table, all the correct columns are shown. However, when I open the layer property box, the attribute columns I want ...
5
votes
2answers
3k views

How to display KML image overlays in OpenLayers?

I am working on displaying Ground Overlays on OpenLayers by parsing KML manually. To do so, I was trying to add an image on top of Google Map by looking at GroundOverlay section from ...
3
votes
2answers
614 views

How to calculate the shared area between a raster and a shape file 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 (Shape file). ...
1
vote
2answers
692 views

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

Regarding yesterday's question about how to speed up band math in the R 'raster' package, would it be the same to use overlay to calculate NDVI instead of calc? If that's not the case, what's the ...