Hot answers tagged overlay
19
You are confusing two different operations dealing with Projections.
Define a projection: You would use this when you have a shapefile or other featureclass, that does not currently have a spatial reference defined when you look at the properties in ArcGIS. You might also use this if you knew based on some observation, that the projection defined for the ...
17
Although you have set the projection of your 3 other layers by the properties menu in ArcCatalog, you have failed to re-project the data to the proper coordinate system.
Please try the Project tool, located in Data Management Tools → Projections and Transformations → Feature.
This should allow you to create a new feature class that is projected ...
10
Direct tile access is not allowed by Google (and this is what ArcBruTile is doing). Usually this will get your IP address banned for awhile but they could also come after you for violating their TOS.
fwiw, Arc2Earth will be adding support for this functionality in the next build. Instead of needing a Google Maps Premium license, you can purchase access at ...
10
Here is how I would do it in a Desktop.
Get Quantum GIS Desktop, an Open Source and popular GIS
Desktop.
Install Openlayers Plugin(In Menu, Plugins -> Fetch Python
Plugins would display the plugin)
Set Project CRS to EPSG:3857
Add Bing/Google Satellite Layer( Plugins -> OpenLayers -> Add Bing/Google)
Add PostGis Layer(Layer -> Add Postgis ...
9
Openlayers can't display rotated images as Layer.Image. If you want to
display rotated images, you can use as workaround a vector layer with point
feature and externalGraphic.
Example of rotation:
http://openlayers.org/dev/examples/rotate-features.html
And example of rotation with graphic:
http://openlayers.org/dev/examples/styles-rotation.html
And ...
9
Okay few things i would change and give another try:
Make sure your featureNS value is in the "Edit Workspace Page under Namespace URI" in your GEOSERVER. Do not use something as generic as "http://postgis.org". Use something like "http://yourdomain/application/catalogLayer" or something unique like that. You can make this URI up, just make it unique.
You ...
9
These are the basic steps you need to run through (is this what you have done? Apologies if this is too basic)...
Make sure that your 1940 shapefile has an attribute containing county
area (e.g. ‘Area1940’)
use the Union tool (ArcToolbox > Analysis Tools > Overlay > Union)
with your 1880 and 1940 shapefiles as inputs.
Specify a new output shapefile.
In the ...
7
That is how it is supposed to work. OpenLayers can't reproject WMS layers for you so you should let the WMS server take care of that for you.
If your WMS can not support EPSG:32628 then you will need to look into setting up a cascading WMS that can reproject it for you (both MapServer and GeoServer 2.1+ can do this).
7
I think the problem is your time span. Its supposed to be in the format
YYYY-MM-DDThh:mm:sszzzzzz (see KML Ref)
"1944-06-06T06:2010-10-26T06:30:08
"
is wrong in the "mm" part. Also, if you're trying to animate a set of time periods rather than points, you need timestamp rather than span.
Time should be before and after according to the documentation ...
7
This is a graph coloring problem.
Recall that a graph coloring is an assignment of a color to the vertices of a graph in such a way that no two vertices which share an edge will also have the same color. Specifically, the (abstract) vertices of the graph are the polygons. Two vertices are connected with an (undirected) edge whenever they intersect (as ...
6
Given the sun's position, you can easily create a grid of the surface light intensity (ignoring atmospheric and topographic effects) in lat-lon coordinates. Reproject that grid as desired and overlay it on the map.
The formulas are the standard ones for spherical coordinates: the unit vector corresponding to a spherical coordinate (lon, lat) is
...
6
Yes. ArcBruTile - Tile Services in ArcGIS Desktop
ArcBruTile display tiles from
OpenStreetMap, Bing, Google,
SpatialCloud and TMS/WMS-C Services in
ArcGIS Desktop.
Update: looks like references to Google have been removed from the ArcBruTile site, likely because, as commenters point out, what they're doing violates the Google Maps ToS.
6
It's not possible to mix geometry types in layers.
You will need to add separate layers.
Also, I'd recommend splitting the layers by topic, e.g. one layer with buildings, one with general zoning info. Don't just throw everything into one layer, otherwise you will have a mess to clean up later. Also styling is going to be easier with more layers.
As @Willy ...
5
What geographic/datum transformation did you use in ArcGIS? There aren't any for Bessel 1841 because that's an ellipsoid, rather than a geodetic datum. Is it really CH1903? Or CH1903+? The use of Bessel 1841 implies to me that the data originally came from a GRID or coverage. CH1903/CH1903+ wasn't supported in ArcInfo Workstation, so only the ellipsoid could ...
5
Just like set intersection, geometric intersection (which is essentially an intersection on two sets with spatially defined bounds) is both commutative and associative, e.g. (A ∩ B) ∩ C = A ∩ (B ∩ C) = (C ∩ B) ∩ A = C ∩ (B ∩ A).
In practice, software often uses the order of inputs to determine how attributes are associated with the output; but the spatial ...
5
OpenLayers can transform vector layers (like WFS). If your vector layer is in EPSG:900913 or EPSG:4326 OpenLayers can handle the transformation itself, otherwise, it needs Proj4js included.
There are examples of how to use OpenLayers with Proj4js.
Raster Layers cannot be transformed by OpenLayers. If you need to include them in a different projection, you ...
5
PBSMapping should fit your needs. There's a tutorial at NCEAS. The code below is adapted from that tutorial. I'm making assumptions about your data btw. Please edit as appropriate for your situation.
library(PBSmapping)
#prepare towns
pts <- read.csv("towns.csv")
towns <- points(towns$lon, towns$lat)
# read in shapefiles
rivers <- ...
5
I would recommend clipping the raster to the shapefile, then in the resulting raster you can look at the number of cells present for each of your classes. The area can be calculated by multiplying the number of cells by the area covered each pixel (cell size squared).
It's a different approach than the equally valid solution offered above but from a ...
4
A couple geometry libraries I'm aware of include:
Java Topology Suite, JTS
Geometry Engine Open Source, GEOS
OGR provides read/write access to many spatial formats and includes many, if not all, of the spatial operations provided by GEOS.
4
This a simple tutorial one can follow to define/transform geographic coordinate system and/or datum in ArcGIs 9.3., starting from a ".csv" file.
Open ArcMap;
In ArcMap, click on “Tools” button located in Main Menu. Choose the
following option: “Add XY Data”;
On “Add XY Data” window, click at the browse button to open the
“.csv” file which contains ...
4
Your line ras_sub0<-rasterize(subarea0,raster_bath) is just taking the index number of the polygons and assigning that to the values of the raster.
If you want just the intersection of your polygon and the raster:
subarea0_bathy <- intersect(raster_bath, subarea0)
Update: As @GodinA notes, looks like intersect() sometimes doesn't return a raster ...
4
v is a list. There is one list element for each polygon. Each list element can have many values (one for each raster cell that it covers). Therefore, you cannot simply combine the data to the SpatialPolygons (and you are not saying why you want to do that anyway). To get a single value for each polygon, you can use extract with a function (mean would be the ...
4
Here is working code:
options = {
div: "map",
zoom: 5,
center: [-10796366.372312, 4426748.6429884],
layers: [
new OpenLayers.Layer.OSM()
],
projection: "EPSG:3857"
};
map = new OpenLayers.Map(options);
var noaaRdr = new OpenLayers.Layer.WMS(
"Latest Radar",
"http://nowcoast.noaa.gov/wms/com.esri.wms.Esrimap/obs?",
...
3
The regular way does not support it (OpenLayers.Format.KML). as you can see this example contains an overlay in france and it does not show up in openlayers but it does in google earth.
http://openlayers.org/dev/examples/sundials.html
http://openlayers.org/dev/examples/kml/sundials.kml
You're going to have to parse it manually and use ...
3
You may want to check out gdaltileindex to see if that is what you want. It will automatically build a 'footprint' polygon for each raster. This may not work though if you have nodata values along the edges that you're hoping to exclude, in which case your #3 seems like proper logic (although perhaps not the most efficient.)
3
What version of arcGIS are you using? if you have arcgis installed try creating a raster mosaic and build foot prints when you do this. Footprints are just the polygon outline of each raster. You could also use arcpy/arcgis to return the stats on each raster with the idea being to create corner points for each raster and create polygons from them.
When I ...
3
I am assuming you are using ArcGIS 10. Let me know if you are using a different version and I will change this for that version.
First, make sure that your result shapefile from the intersection is in a projected coordinate system. It should be with the actions you have done already, but it is a good idea to check.
Run Dissolve (Data Management > ...
3
The low-level spatial predicate operators are all binary—i.e., compare geometry A to geometry B. For example, see the DE-9IM topological model, which is the basis for Intersects, Contains, etc. When you have more than two, say geometry C, then you might need to compare the combinations of geometries: AB, AC, BC. But it all really depends on what you are ...
3
Google Maps doesn't use WGS84. Try re-projecting the original data to EPSG:3857
+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs
ESRI used to use Web Mercator Auxiliary Sphere (WKID 102100) or Web Mercator projection (WKID 102113). You can download the .PRJ file from spatialreference.org.
3
The simplest way to overlay two plots might be using the add = TRUE option in plot. Here is an example with artificial data
# Load sp package for creating artificial data
library(sp)
# Create sample town points
towns <- data.frame(lon = sample(100), lat = sample(100))
towns <- SpatialPoints(towns)
# Create sample polygon grid
grd <- ...
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