I want to know what is the main methods that used in GIS to connect between the location and their information (spatial access methodes) SAM.
I read in some web sites two methods are:
vector
raster
is that methods related what I want???
thank you ^_^
there are indeed in general two types of GIS datasources: Vector and Raster.
With vector; the attribute data can be stored in several ways:
- Side by side in a spatial database
- In a vector file paired with an attribute file (ESRI shape with ESRI dbf)
- Connected in an application (f.i. in MapInfo; connecting points to an excel sheet based upon a common attribute)
With raster; all you have is the numeric value of a pixel.
The process of connecting data to geo-spatial coordinates is called Geocoding.
Other common methods use simple coordinates (Lat/Long or GPS).
Vector/Raster refers to the two main types of graphical data that a GIS might use to render a map.
Related
I have a mobile app heavily associated with maps, GPS, location etc.
Currently I'm sending real time location data to server as regular Json (Strings...), and in the server I'm converting it to my custom geo objects, querying geo spatial database (PostGis etc.). Then backwards: I'm converting the results to strings and send them back to client as regular Json. Usually the client needs this results to display them to the user, so it's convenient that they are already strings.
My question is what can I benefit from working with Geo Json format instead? It's clear that it enables "offline mode" using SpatiaLite etc. But what else? What about all the conversions I'm using from/to strings of geo locations? Currently I have some very simple custom geo objects (location object etc.). Can I benefit here? Note that in the end it's good for me have the results as strings for the user, and for now offline mode irrelevant.
Is there a rule of thumb that if you are location/map app - it's best practise to use geo Json and not regular Json?
Thanks,
The benefit of using geojson instead of pushing out values as string is that geojson is a documented, specified format. Client-libraries (like d3.js) can make use of it and make transformations, projections and other geo-related operations on the client.
If the format benefits you in your current project depends on the libraries and framworks you use with your client. If for example your Project only needs geo-xml or kml output, geojson will be of no use for you.
I will need all the help of the experts!
I do have an mysql db which instead of spatial data has gazetteer uri's...
I was asked to build a dynamic map with openlayers (or any another js framework) but I don't know how to proceed or how to start !!!
Shall i transform the db into spatial somehow?
--Although they may not allow me to mesh with their db.
Alternative can I somehow create a layer on the fly?
--layer features will come from mysql
--spatial info from the gazetteer
Can this be done at openlayers level ? Are you aware of such capability of geoserver/mapServer so as the later serve such a layer through WMS ??
Also other strategies/ideas are more than welcome !!
thx
g.
I'm working on an app that uses json to get coordinates from a website. So, my question is: what's the best variable type that I should use to store the coordinates from the website. I'm new to Xcode, and I don't really know the types of variables that are permitted.
You could probably use a CLLocation object to store that data. CLLocation will also give you helpful methods for determining the distance between two points, if you need to do that kind of thing.
I have a shapefile with around 19,000 points. Its basically export from a raster. Now i need to extract polygons, by aggregating the points which have same value.The field who's value i am going to use for aggregation is dynamically calculated each time using the elevation of points. NOw i need to spit out polygons. How can I do that using GDAL? is there a utility to do it. Any other opensource solutions are welcome.
I have ArcGIS which has a toolbox called 'Aggregate Points' but somehow licence for it is missing.
Here are some possibilities:
You can write a program using GDAL (actually OGR) in C++ or Python (or any other language for which GDAL/OGR provides bindings) and construct Polygon objects from the selection (sub-sets) of your points. Then you can serialise those polygons in to Shapefile or anyother storage supported by OGR.
Alternatively, forget about GDAL/OGR and load your data into PostgreSQL database enabled with PostGIS. Then use PostGIS functionality to construct Polygons
There is example of polygon construction from points based on bruteforce string manipulation and use of geometry constructor posted as postgis-users thread Making a Polygon from Points
I'm thinking about developing an application where I got geodata stored in a geo-database with Sql Server 2008. I like to retrieve this data and paint the different shapes with svg, embedded in html5.
My question is:
How could I possibly retrieve this data,using what? I think some script language like php would do the job. Is there a way to do that only with javascript? Also is there a way to develop that using a microsoft technology(which i would prefer).
Thanks in advance
Sebastian
I have done 2D vector graphics using SVG, based upon Garmin Edge XML Points:
http://www.mtbbikeshop.dk/ruter
Two views: Topography or Google Maps
I extacted XML data and made a lot of calulations in order to produce POLYGON points
I used PHP on server side to prepare and transform. At client end I assembled the data, using div/span
But I am not sure want kind of vector you need ?