I have a data set with over 50,000 geocoded points (lat-long). Each point has a set of data associated with it -- things like quality, status, etc.
I'd like to make a set of density maps showing the distribution of data by those metrics. For example, one map would show the density of all items with a quality of "good".
With a smaller set of points, I'd use Google Maps and custom markers. Here, however, different segments have tens of thousands of points
Are there any APIs or libraries that could help me do this?
The solution I will be going with:
Break the area to be mapped into a
grid.
Count the number of entries
falling inside each square.
For each
square, generate a PNG with
transparency relative to the number
of entries.
Populate a Google Map with
this set of PNGs as markers.
Google Fusion Table does a nice job at it http://www.google.com/fusiontables/Home/
Good for you that your data are already geocoded, because -from my recent experience-, Google location resolver does not let you dealing with ambiguous location..
One solution could be to create bitmaps with your density maps and add them (only one at the same time) as overlay on your google map (with GGroundOverlay)
You may have a look at this post that gives an example of density map with google map. It uses the HeatMapAPI. Unfortunately, this API is not free if you use it with a large number of points...
Put build your own density bitmap may be not so complicated...
One other solution is to reduce the number of markers you can use. It could be done with the MarkerClustered library. It is not exactly a density map, but... can maybe be useful.
http://heatmap.codeplex.com/
Related
I'm currently an MS student in Medical Physics and I have a great need to be able to overlay an isodose distribution from an RTDOSE file onto a CT image from a .dcm file set.
I've managed to extract the image and the dose pixel arrays myself using pydicom and dicom_numpy, but the two arrays are not the same size! So, if I overlay the two together, the dose will not be in the correct position based on what the Elekta Gamma Plan software exported it as.
I've played around with dicompyler and 3DSlicer and they obviously are able to do this even though the arrays are not the same size. However, I think I cannot export the numerical data when using these softwares.I can only scroll through and view it as an image. How can I overlay the RTDOSE to an CT image?
Thank you
for what you want it sounds like you should use Simple ITK (or equivalent - my experience is with sitk) to do the dicom handling, not pydicom.
Dicom has built in a complete system for 3D point and location specifications for all the pixel data in patient coordinates. This uses a bunch of attributes in the dicom files in the Image Plane Module set of tags. See here for a good overview.
The simple ITK library fully understands and uses the full 3D Image Plane tags to identify and locate any images in patient coordinates by default - irrespective of such things as the specific pixel spacing, slice thickness etc etc.
So - in your case - if you use SITK to open your studies, then you should be able to overlay them correctly "out of the box", because SITK will do all the work to parse the Image Plane Module tags and locate the data in patient coordinates - just like you get with 3DSlicer.
Pydicom, in contrast, doesn't itself try to use any of that information at all. It only gives you the raw pixel arrays (for images).
Note I use both pydicom and SITK. This isn't something bad about pydicom, but more a question of right tool for the job. In fact, for many (most?) things I use pydicom, but for any true 3D type work, SITK is the easier toolkit to use.
Is there a way to generate heat maps by zip code using Power Maps for Excel. I have build it using region and it does appear to have a heat map scaling for the color range. However the difference in the color range being used it not noticeable. So maybe I just need a way to adjust the color range.
I tried using the heat map option but all the zip codes have a ring for all the colors even though there is only one value per zip code. Also the zip codes blendtogether and form you giant blob of red.
If there is a different free option you would recommend for doing this type of mapping I am open to suggestions. I previously used MapPoint but that is no longer an option.
You could change the look of your Power Map. You could also change the color for one or more data series.
Please refer to the following link:
Geocode your Power Map data
Change the look of your Power Map
Change the color of a data series in 3D Maps
I studied the multimarker documentation of ARToolKit for iOS and i have some troubles in achieving some sort of QR-Code.
I want, for example:
A set of 6 markers positioned differently on a picture, and when and only when ALL of them are present, some sort of video is displayed in the origin of them( i want to use some sort of CORNER Markers like QR-Code system ).
How to do this ? From what i've seen, on multimarkers, if 1 is present out of 6 for example, the object is displayed.
From looking into the ARToolKit code you can see that a MultiMarker is internally handled as one single Marker consisting of several Pattern:
https://github.com/artoolkit/artoolkit5/blob/master/lib/SRC/ARWrapper/ARMarker.cpp#L344
https://github.com/artoolkit/artoolkit5/blob/master/lib/SRC/ARWrapper/ARMarkerMulti.cpp#L75
That is why ARToolKit will always return true whenever one of the markers configured in the multi-marker configuration is visible.
Taking that into account ‘Multi-Markers’ are not the way to go for the target you would like to reach.
What you can do, however, is to configure each marker separately and add them as ‘Single-Marker’. Then you can query if all of these ‘Single-Markers’ are visible.
If so you can calculate the origin of all these ‘Single-Markers’ and render your object there.
You can get an idea on how to configure several ‘Single-Markers’ if you take a look here:
http://augmentmy.world/moving-cars-augmented-reality
Also take that example here on how to set to markers into the same coordinate system (and calculate the distance between them) you can use that as a starting point for calculating the origin between several markers:
https://github.com/artoolkit/artoolkit5/tree/master/AndroidStudioProjects/ARMarkerDistanceProj
I know that these are not iOS examples but I have only done Android so far. Also, the ARWrapper interface should be the same on Android and iOS, meaning to say there should not be much difference between these two.
I hope that helps
When a user taps a point on an MKMapView in my application, I want to determine what country they tapped on. Speed is my priority, since a user will definitely notice the lag between a map touch and an annotation callout begin presented with the name of the country.
I have the polygon information for all the countries and I can parse/store them in any kind of data structure necessary. Currently, they are in GeoJSON format and have thousands of verticies. I also have bounding boxes computed and stored for each country.
One suggestion was to store an array of CGRects for each polygon's bounding box and first doing a CGRectContainsPoint search on all the bounding boxes to quickly narrow down the search. If that search returns multiple bounding boxes (common on country borders where the bounding boxes can overlap) then I can check the filtered country's full polygon for the point in question. Even on very congested overlapping areas, this full search would be 5 or less full country polygons to check.
To accomplish this, I'll need to store both a CGRect bounding box and a full, complex CGPath for each country. (and a country can have multiple polygons if it has territories) I don't know if storing these in-memory is a good idea, since there are potentially many thousands of polygons.
Compiling SpatiaLite is not an option because of the licensing requirements for GEOS. Compiling SQLite with the R-Tree extension is a possibility. The polygons do not change, so I'm able to precompute and store them on disk in any way that is suggested.
If I follow this suggestion, what is the best way to store and access all these CGRect and CGPaths for quick searching and access?
I'm open to any other suggestions people have.
I would recommend either using the Mapbox iOS SDK or at least using the RMInteractiveSource and RMMBTilesSource parts of it. You can use TileMill to turn your source data into raster tiles with encoded interactivity info on a per-pixel basis. Here's an example: https://github.com/mapbox/mapbox-ios-example The interactivity data is basically a highly efficient key-value store on a per-pixel basis. You can then convert a CGPoint at a given map zoom level and panning offset into the value.
Technology background: https://www.mapbox.com/developers/utfgrid/
I see some ways to do it:
1) Draw using OpenGL programmatically.
2) Draw using QuartzCore and CoreAnimation programmatically.
3) Draw map in AutoCad and then somehow connect it to iOS.
4) Draw map using SVG.
Requirments are supporting pathfinding and gps navigation.
For first 2 ways I think that it's expensive in terms of performance way, redraw all elements on scaling; and I don't think that this way may have GPS-navigation support.
Using AutoCad pictured maps is hard to understand for me how to connect it with graphs\paths for pathfinding.
My colleagues will develop this app on web using SVG. I found it - https://github.com/SVGKit/SVGKit , but still have no idea how it will support pathfinding and navigation.
I would appreciate any help.
Generally there are two types of map application:
A) They display a map, (with or without a user position) without needing to calculate a path like a navigation system does (see point B)
B) Application that use the vectors of a map and calculate something: e.g to find a best path. The shortest connection, e.g A navighation system , etc.
Application for A) are usually less complex then that of B), because the vectors can be somewhat inacurate, have no conections, have small gaps, have no logic between the edges, etc.
1) To only display a building map, you would only need a list of edges. (An edge is pair of coordinates (x1,y1) - (x2,y2). How ever you get that. E.g MapInfo Professional format mif/mid.
Or even you could dispaly a pdf that contains the map of the builing. Right with the built in PDF View, (also with SVG but more difficult).
Things get much more complicated if it is not a relative map, but also a map that is positioned with an reference coordinate system, like latitude/longitude (WGS84).
In that case you would use a Tool (mapInfoProfessional, to import AutoCad DXF Files, and apply 3 GPS measured reference points at the corner of the house, and convert that to LatLong WGS84 coordinates system.
With ios you cannot measure that 3 Points because you cannot average a position, ios stops sending when you are standing still at one corner of the house.
You could try to extract the positions from a google earth satellite foto if you are living in a region where google Sattelite fotos have high resolution. (But this might violate the license conditions of that Satellite Foto provider (Topic: derived data))
Finally you now have a list of edges in Lat Lon coordinate System.
For Displaying I personally would either do with 1) OpenGL) or 2) Quartz2D.
Now the Path finding part.
Probaly you need a second "map" that defines the possible paths inside the building.
This structure must be a connect graph (points with connected neighbours).
Computer games do it that way. (Some even allow you to display that path in developper mode)
The path can be drawn, in a different layer of the floor plan. But this path
has higher requirements: No gaps are allowed, all must be perfect connected.
Call that layer "Path" and export it as own plan.
Now use only this path layer, and import, and create a graph of nodes with connect neighbours.
Use Dijkstra Algo to search for shortest path.