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4

I think there is no better way than to handle zoomend event. To group markers by zoom levels, use L.LayerGroup: turning them on and off will be easier. Calling map.removeLayer() or map.addLayer() twice won't produce any errors or add a layer twice: there is an internal hash that prevents such things. So you can just have a bunch of if (zoom > 6 ...


4

You can't efficiently delete large numbers of features from a large table, period. You'd be much better off just marking them as deleted (available varchar(1), values 'Y' or 'N') and adding an attribute constraint to your selection logic (or using a view). Building a parallel table to house a foreign key and available field is an adequate solution, though ...


3

You'll want to to ensure that both of the layers are in the same Coordinate System. Add a new field in the BG Data, and calculate the area, bg_area. Run Intersect on your custom polygons and the BG data to create an intersection layer. Ensure that you have the area of your custom polygons calculated. Arc should automatically calculate this in Shape_Area. ...


2

Expanding my original comment: Topojson can work fine with openlayers 2.10 (you actually convert topojson to geojson prior to using it). But I'm not sure it would solve your problem as it may still be too big to process in most browsers. An example on using topojson in openlayers 2, based on the openlayers geojson example and some data I used in a blog ...


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I believe you are looking for an 'intersect' operation. This leaves only the full extent covered by both inputs (where both overlap) but with polygons split and attributes combined from both. In QGIS (v2.0) go to your 'Processing' menu and click 'toolbox'. Geoalgorithms > Vector > Overlay > Intersection In QGIS (v1.8) Go to: 'Vector' menu > Geoprocessing ...


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Even if you find historical maps that use a cylindrical projection, or even Mercator projection, they're not going to overlay without further work. Even in the Mercator case, the datums or projection parameters will be different. You can try to georeference the historical map to reference data that's in a coordinate system as close as possible to the one ...


2

This might be a way. I use this World map shapefile # Read in new shapefile world <- readOGR("~/test", layer="TM_WORLD_BORDERS-0.3") # Order after $REGION in the 8th column world_attri <- world@data[ order(-world@data[,8], world@data[,1]), ] # Extract first line of each unique $REGION world_attri <- world_attri[!duplicated(world_attri$REGION),] # ...


2

Here's one way, using Numpy and GDAL. Read your 125m resolution raster into an array that is 25x larger in each dimension. GDAL's I/O function decimates for you and this feature is available in Rasterio (https://github.com/mapbox/rasterio/blob/master/docs/windowed-rw.rst#decimation) and I assume also in osgeo.gdal. Ask the methods to write into an array ...


2

What you're trying to do is known as apportionment. This takes a numerical attribute value of a feature and divides it in some way between pieces that feature is split into. There are a number of different solutions. In fact, there's a specific tool for it in the Business Analyst extension, but you probably don't have that. Esri has also published a ...


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The simplest solution is probably to create a topology with the Must Not Overlap rule, select all errors in the Error Inspector window, right-click and choose Substract: You can find out how to create a topology here if necessary. You can create the topology, add feature classes and rules with ModelBuilder with the tools from the Topology toolset, but you ...


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Your problem is that WFS 1.0.0 does not support reprojection of the coordinates. If you switch your request version to 1.1.0 then GeoServer will take your srs into account.


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I would use the georeferencer to get the jpeg in the correct position and then digitise the lines/boundaries so that you dont have to have the jpeg in the model anymore


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Frequency and summary statistics were definitely present in version 9.2, frequency has been around since I've been using ESRI products (early 1990's). Summary Statistics offers more powerful statistic types over frequency, and can work with a basic license (ArcView) where frequency needs advanced (INFO) license. Same with Intersect, Identity and Union, ...


1

If you do not need the bathymetry, then don't combine the sea raster with the land elevation raster. Instead use it as a mask as follows: Make your sea polygon into a raster: v.to.rast sea output=sea use=value val=1 Then make a land area raster ("inverse" of the sea): r.mapcalc "land_area = if(sea==1, null(), 1)" Now set the land_area as a mask, and ...


1

you seem to have just two cases, so a conditional statment (using map algebra or raster calculator) could help Con( IsNull(C4), float(C1 + C2 + C3)/3 , float(C1 + C2 + C3 + C4)/4) In this case you apply a weighted overlay (with the same weight) that is different with or without NoData in C4. Note that you can change the weights if you want (see below): ...


1

there are two main logical operators : the AND and the OR. In fuzzy logic, you can use: "fuzzy AND" as an equivalent of the minimum of the different membership values "fuzzy OR" as an equivalent of the maximum of the different membership values if you want to combine this with your crisp decision, you can convert "yes" to 1 and "no" to 0. Then you can ...


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What I want to know is the number of the red dots that are present in just one area defined by the black line. Vector | Analysis Tools | Points in Polygon will count the number of points for each polygon. Update: Since your "dots" are indeed lines - as the icon in the layer list indicates - try using Vector | Analysis Tools | Sum Line Lenght. It adds ...


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You can find a lot of historic maps online digitized by American Libraries. A few examples: http://www.lib.utexas.edu/maps/ http://lib.byu.edu/digital/germanmaps/ http://www.wildernis.eu/chart-room/ Unfortunately, Only few write the used projection onto the map. Cylindrical Projections are common for Northern America. In Europe, Mercator and Transverse ...


1

I managed to create an FME workbench which does what you want with relatively few transformers. I created a line feature class with two lines which cross several property boundaries. Here's a screenshot of my workbench with summary annotation (I'm aware it may look small on screen, but you can view the image in a new window and it should appear larger): ...


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I would recommend writing a python script for this task (which you could incorporate into a script tool). The general script flow would go something like this: Add text field to polyline layer (preferred use a polyline geodatabase feature class) Make feature layer of the polyline layer Use update cursor on feature layer and pull out each ID value that you ...


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Why dont you try the swapping lat/long: Load your gpx data use the swapxy plugin to swap between latitude and longitude save the swapped gpx data in any vector format


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You could split the data in to GeoJSON files and name them according to tile. Once the map loads, you could query for the visible tiles and use their names/urls/coordinates to request the appropriate GeoJSON files, matching one file per tile. The hard part is creating the files. For this, you definitely need to use a tool. Once the files are created, ...


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This sounds like a job for D3 - http://bl.ocks.org/mbertrand/5218300


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The gif file does not have any georeference information (like geotiff has). So you have to tell QGIS that the upper left corner is -180°E/90°N, upper right is +180°E/90°N, lower right is +180°E/-90°N and lower left corner is -180°E/-90°N. The georeferencer is the tool to do this. Without that information, QGIS treats the upper left corner as 0°E/0°N, ...


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Intersect Layer 1 and Layer 2 (Vector > Geoprocessing Tools > Intersect) Dissolve result from step 1 (Vector > Geoprocessing Tools > Dissolve). Use name of properties/ id of properties as dissolve field. Add new field to result from step 2 and calculate area:



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