Ideas

Satellite orbits in Google Earth

The last section of mapping toolbox of MATLAB deals with KML files. You can compute a lot using the toolbox, export the result as KML and the user can just import them into his GOOGLE EARTH and view for free. This way the user uses one familiar, versatile and free viewer for all your files.

A real time problem.

Ordering images from NRSC website and ordering toposheets from SOI is a real challenge, the reason - there is a whole lot of parameters to be kept in mind. A major issue is to know the satellite path and the time at which it would fly over a particular region. If you can compute the orbit of a satellite and supply that as a KML, I can load it in my google earth and get to know at what date the satellite would fly over my area of interest. I will also know the path, row information which makes ordering easier. Added to all of that, I see the study area on google earth which gives me a whole lot of comfort before ordering, for sure I would know I am ordering the right scenes for my area. In reality, everyone first sees their study area on Google Earth before placing an order, so if you club them ??!! thats novelty.

Second, you can bring the same concept for SOI toposheets, I will get to know the sheet numbers easily before placing an order.

GeoTiff Outliner

Locates the 4 corners of georeferenced image surrounded by background cells and makes a shape file.

GeoTiff Path Row

Program to generate path-row polygon shapes from a set of georeferenced

satellite images.

In large scale mapping projects with numerous satellite images, it is useful to have a vector file depicting the boundary of the images. This script when run from the folder containing the images, it automatically detects the geotiffs and extracts their image area boundary and constructs a polygon shape file containing the boundary of all images.

The name of the image file is given as the attribute information for each polygon. Ideally, the images are expected to be named with their path-row numbers.

GeoTiff_PathRow.m can be downloaded from here

Polar orbiting remote sensing satellites have an orbital inclination of about 9 degrees to the vertical. Because of this georeferenced satellite scenes are not straight but slanting (rotated). It is generally useful to have a vector containing the boundary of the image. Since an image can inherently be only a rectangle, such satellite images have bounding background pixels with 0 fills. Using a default MATLAB function to extract the boundary of this image would only provide the corners of this entire image with 0 fills as a rectangle.

This program is optimized. It starts reading from the top row down till the top left corner of the image is reached. Then is starts reading from left to right to get the top right corner and similarly for other two corners. This way it does not actually read the entire image but only the corners. It dynamically reduces the process time when we have a very large image with relatively small background 0 fills.

GeoTiff Outliner can be downloaded from MATLAB Central or from here