Tutorials: moved imgcodecs and videoio tutorials to separate pages

doc/tutorials/imgcodecs/raster-gdal/raster_io_gdal.markdown

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+Reading Geospatial Raster files with GDAL {#tutorial_raster_io_gdal}
+=========================================
+
+Geospatial raster data is a heavily used product in Geographic Information Systems and
+Photogrammetry. Raster data typically can represent imagery and Digital Elevation Models (DEM). The
+standard library for loading GIS imagery is the Geographic Data Abstraction Library [(GDAL)](http://www.gdal.org). In this
+example, we will show techniques for loading GIS raster formats using native OpenCV functions. In
+addition, we will show some an example of how OpenCV can use this data for novel and interesting
+purposes.
+
+Goals
+-----
+
+The primary objectives for this tutorial:
+
+-   How to use OpenCV [imread](@ref imread) to load satellite imagery.
+-   How to use OpenCV [imread](@ref imread) to load SRTM Digital Elevation Models
+-   Given the corner coordinates of both the image and DEM, correllate the elevation data to the
+    image to find elevations for each pixel.
+-   Show a basic, easy-to-implement example of a terrain heat map.
+-   Show a basic use of DEM data coupled with ortho-rectified imagery.
+
+To implement these goals, the following code takes a Digital Elevation Model as well as a GeoTiff
+image of San Francisco as input. The image and DEM data is processed and generates a terrain heat
+map of the image as well as labels areas of the city which would be affected should the water level
+of the bay rise 10, 50, and 100 meters.
+
+Code
+----
+
+@include cpp/tutorial_code/imgcodecs/GDAL_IO/gdal-image.cpp
+
+How to Read Raster Data using GDAL
+----------------------------------
+
+This demonstration uses the default OpenCV imread function. The primary difference is that in order
+to force GDAL to load the image, you must use the appropriate flag.
+@code{.cpp}
+cv::Mat image = cv::imread( argv[1], cv::IMREAD_LOAD_GDAL );
+@endcode
+When loading digital elevation models, the actual numeric value of each pixel is essential and
+cannot be scaled or truncated. For example, with image data a pixel represented as a double with a
+value of 1 has an equal appearance to a pixel which is represented as an unsigned character with a
+value of 255. With terrain data, the pixel value represents the elevation in meters. In order to
+ensure that OpenCV preserves the native value, use the GDAL flag in imread with the ANYDEPTH flag.
+@code{.cpp}
+cv::Mat dem = cv::imread( argv[2], cv::IMREAD_LOAD_GDAL | cv::IMREAD_ANYDEPTH );
+@endcode
+If you know beforehand the type of DEM model you are loading, then it may be a safe bet to test the
+Mat::type() or Mat::depth() using an assert or other mechanism. NASA or DOD specification documents
+can provide the input types for various elevation models. The major types, SRTM and DTED, are both
+signed shorts.
+
+Notes
+-----
+
+### Lat/Lon (Geographic) Coordinates should normally be avoided
+
+The Geographic Coordinate System is a spherical coordinate system, meaning that using them with
+Cartesian mathematics is technically incorrect. This demo uses them to increase the readability and
+is accurate enough to make the point. A better coordinate system would be Universal Transverse
+Mercator.
+
+### Finding the corner coordinates
+
+One easy method to find the corner coordinates of an image is to use the command-line tool gdalinfo.
+For imagery which is ortho-rectified and contains the projection information, you can use the [USGS
+EarthExplorer](http://http://earthexplorer.usgs.gov).
+@code{.bash}
+\f$> gdalinfo N37W123.hgt
+
+   Driver: SRTMHGT/SRTMHGT File Format
+   Files: N37W123.hgt
+   Size is 3601, 3601
+   Coordinate System is:
+   GEOGCS["WGS 84",
+   DATUM["WGS_1984",
+
+   ... more output ...
+
+   Corner Coordinates:
+   Upper Left  (-123.0001389,  38.0001389) (123d 0' 0.50"W, 38d 0' 0.50"N)
+   Lower Left  (-123.0001389,  36.9998611) (123d 0' 0.50"W, 36d59'59.50"N)
+   Upper Right (-121.9998611,  38.0001389) (121d59'59.50"W, 38d 0' 0.50"N)
+   Lower Right (-121.9998611,  36.9998611) (121d59'59.50"W, 36d59'59.50"N)
+   Center      (-122.5000000,  37.5000000) (122d30' 0.00"W, 37d30' 0.00"N)
+
+    ... more output ...
+@endcode
+Results
+-------
+
+Below is the output of the program. Use the first image as the input. For the DEM model, download
+the SRTM file located at the USGS here.
+[<http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/Region_04/N37W123.hgt.zip>](http://dds.cr.usgs.gov/srtm/version2_1/SRTM1/Region_04/N37W123.hgt.zip)
+
+![Input Image](images/gdal_output.jpg)
+
+![Heat Map](images/gdal_heat-map.jpg)
+
+![Heat Map Overlay](images/gdal_flood-zone.jpg)

doc/tutorials/imgcodecs/table_of_content_highgui.markdown

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+Image Input and Output (imgcodecs module) {#tutorial_table_of_content_imgcodecs}
+=========================================
+
+This section contains tutorials about how to read/save your image files.
+
+-   @subpage tutorial_raster_io_gdal
+
+    *Compatibility:* \> OpenCV 2.0
+
+    *Author:* Marvin Smith
+
+    Read common GIS Raster and DEM files to display and manipulate geographic data.