At nighttime, the visible wavelengths do not measure anything and is just black. There is information, however, from other channels we can use to see clouds at night. To view clouds in portions of the domain experiencing nighttime, we will overlay the clean infrared IR channel over the true color image.
First, open a file where the scan shows partial night area and create the true color RGB as before. When you print the contents of channel 13, notice that the unit of the clean IR channel is brightness temperature , NOT reflectance.
We need to normalize the values between 0 and 1 before we can use it in our RGB image. In this case, we normalize the values between 90 Kelvin and Kelvin.
We want to overlay these two images, so the clean IR fills in the night sky on the True Color image. This way we can still see the clouds at night. To fill in the dark area on the true color image, we will set each RGB channel to equal the maximum value between the visible channels and the IR channels.
Note that if the clean IR has really bright, cold clouds in the daylight, they will replace the color values in the true color image making the clouds appear more white. I think the color looks a little dull. We could get complicated and make a Rayleigh correction to the data to fix the blue light scattering, but that can be intense.
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Skip to main content. Begin by downloading that file to view the examples in Google Earth. The KML 2. The simplest kind of KML documents are those that can be authored directly in Google Earth—that is, you don't need to edit or create any KML in a text editor.
Placemarks, ground overlays, paths, and polygons can all be authored directly in Google Earth. A Placemark is one of the most commonly used features in Google Earth. It marks a position on the Earth's surface, using a yellow pushpin as the icon.
You can specify a name and a custom icon for the Placemark, and you can also add other geometry elements to it. This folder includes three different types of placemark: simple , floating , and extruded. The KML code for the simple placemark looks like this:. If you were wondering where the Placemark is, it's right over Google's Building 41, where we developed Google Earth!
By default, the icon is the familiar yellow pushpin. The Point is used to place the icon, but there is no graphical representation of the Point itself. You can add links, font sizes, styles, and colors, and specify text alignment and tables. Google Earth 4. Ground overlays enable you to "drape" an image onto the Earth's terrain. Notice that the file begins with the same two lines as the first example: the XML header and KML namespace declaration. This example uses a Folder titled "Ground Overlays" as a mechanism to group and label its contents.
Bounding values are given for the north and south latitudes, and east and west longitudes. In addition, rotation values are given for images whose y -axis doesn't coincide with grid north. This example uses a JPEG image for the overlay.
Many different types of paths can be created in Google Earth, and it is easy to be very creative with your data. Take a look at the "Absolute Extruded" example in the Paths folder and you can see how the shape has been generated by the following code:.
Notice how it is really just one line drawn at altitude above the ground. You can use Polygons to create simple buildings and other shapes. The Pentagon example is generated by drawing simple inner and outer shells and then extruding them down to the ground.
Here is the code :. Google map or Google Earth makes use of KML or keyhole markup language, to display features, which actually stores geographic features in Vector format. Before creating KML file on Google map, you should have an Google account and should be logged in wtih that.
You can also look link for how to create KML file from Google earth. Note: Google provides Google map and this kind of service for free.
But i suppose, if you are going to extract and create KML file with your program in bulk, then Google may notify you for the same.
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