One of the exciting features of Starry Night is the ability to simulate your local landscape by adding 360º photos of your own backyard and favorite observing sites. By default Starry Night comes with several photorealistic horizons that you can use when viewing from the Earth. This section will help you learn the basics on how to add your own custom horizons! Not only can you make your own photorealistic horizons for Earth, but also for any planet and many moons in the solar system.
If you’d like to share your own photorealistic landscape with other Starry Night users, you can submit your final work tous (no .zip files please).
Note: Photorealistic horizons require an OpenGL capable graphics card. If you want to replace or edit one of our existing horizons, you need to remove both the "cache" folder and the related "dds" folder found under Sky Data/Horizon Panoramas.
Horizon Panoramas Folder
The photorealistic landscapes are stored in a folder named “Horizon Panoramas”. In Windows you can find this folder under Starry Night <product name>\Sky Data on your local hard drive. On a Mac, Ctrl-click on the Starry Night application and select "Show Package Contents" from its contextual menu. Open the Contents-Resources-Sky Data-Horizon Panoramas folder.
This folder contains a number of images and text files. Notice that each image has a corresponding text file. The image is the completed panorama image and the text file describes how this image will be inserted in Starry Night along with a number of options that will be described below (See Text file Considerations).
Your custom image with the occupying text file must be placed in the “Horizon Panoramas” folder in order for them to be loaded into Starry Night.
We will use the Earth_01Grass.psd and Earth_01Grass.txt files, located in the “Horizon Panoramas” folder, as examples in this help file.
Taking 360º Landscape Images
Instruction on how to take images to construct a 360º panorama image is beyond the scope of this help file. Briefly, you take a series of single overlapping images to get a complete coverage of the horizon around you. You them stitch these images together to form a 360º image. Some digital cameras have panoramic modes that guide you through the process, making them quite handy in taking images to construct panoramas.
Your panorama image must have certain properties in order to work well in Starry Night.
- Must be a 360º degree panoramic image
- 8:1 aspect ratio: no less than 2048x256 pixels; recommended is 4096x512 pixels
- Image is in PSD (Photoshop) format
Image Processing Tips
The following tips for image processing make use of Photoshop, although other image editing programs can be used.
Step 1. Your raw images will look something like the ones below. The first step is to stitch them together to form a continuous panorama image whose ends match exactly. This is an important step and special care must be taken, otherwise seams will be visible in your final image. Several commercial packages are available to help you.
Step 2. The image below shows a stitched 360º panoramic image. This is the most challenging step in creating your own custom landscapes for use in Starry Night.
Step 3. After the image is stitched, use the eraser tool - or a skillful hand with the magic wand and delete key - and remove the sky from your image. The sky is not required because Starry Night will simulate it.
Step 4. The next important step is to add an Alpha channel. Select your 'solid' horizon and add an alpha channel. The black represents 'no transparency' (so that your foreground is opaque) and the white represents '100% transparency' (so that your horizon's sky is transparent and Starry Night can fill it in for you.) Consult your image editing software's manual on how to add an alpha channel to an image. Although optional, the Alpha channel allows you to only see the horizon in your final image.
Turning only the alpha channel on, results in the image below. Ensure that the white area represents the sky.
Step 5. When you save the image, save it in “PSD” format and ensure the Alpha Channels and Layers boxes are checked. The final image looks something like the image below.
Text File Considerations
The second component required to add your photorealistic landscape to Starry Night, is the accompanying text file. For this example, you can use the Earth_01Grass.txt files as a template. Make the appropriate modifications to this file and then save it with a different name.
When you open the Earth_01Grass.txt file, you will see numerous lines with the general format: <SN_VALUE name="XXXXX" value="XXXXX">. These lines allow you to change a number of properties for your photorealistic landscape. The most important lines are mentioned below. You only need change these to successfully add your image. You may leave all other lines and values as they are.
<SN_VALUE name="PanoName" value="Grass">
Change value="Grass" to a name that describes your image. For examplevalue="MyHorizon". The name you choose will appear in the drop box in the Horizon Options window.
<SN_VALUE name="ImageFileName" value="Earth_Grass.psd">
The name of the image you made and placed in the Horizon Panoramas folder. For example if you named your image "MyHorizon.psd", change it to value="MyHorizon.psd". Both the image and text file must be located in the Horizon Panoramas folder.
<SN_VALUE name="ImageHeight" value="55.500000000000000000">
This value specifies the height of the image in degrees. A value between 45-55 is about right for most images.
<SN_VALUE name="UseImageAlpha" value="Yes">
Leave this value as yes if you added an Alpha channel.
<SN_VALUE name="ImageCentreDec" value="-11.000000000000000000">
Think of ImageCentreDec as degrees Up and Down. A value of -11.0 means that the centre of your image lies 11 degrees below Starry Night's formal horizon line. (SN's formal horizon line lies at 0 degrees Altitude as you may expect.) Use this value to adjust your panorama until it looks right against the sky. (You can even set this precisely by recording the actual rise or set time of a certain star/planet over a given obstacle in your panorama -e.g. a mountain peak- and set the ImageCentreDec so that it appears the same in SN.)
<SN_VALUE name="ImageCentreRa" value="0.000000000000000000">
Think of it as Left and Right. Adjust this value if your image is facing towards the incorrect cardinal direction.
<SN_VALUE name="PanoBrightness" value="1.00000000000000000">
Adjusts the brightness of your horizon. The panorama brightness will be scaled with this value, up to a maximum of 1.0 (100%). If you want your panorama to appear half as bright, use a PanoBrightness value of 0.5 (50%).
<SN_VALUE name="PanoApproxColor" value="40192, 39936, 38400">
Used during liftoff. Defines the RGB values for the color drawn behind the horizon.
<SN_VALUE name="Preload" value="Yes">
Preloads the image when Starry Night Starts.
Tip: You can have multiple images preloading when the program starts. However, this will increase the time that it takes for Starry Night to load. Ideally you only want one image to have a preload value of ‘Yes’, the one you use most often.
In addition, when Starry Night loads, the horizon that is displayed by default is the one whose accompanying text file was read first in alphanumeric order from the Horizon Panoramas folder. For example, by default when you run the program the Earth_01Grass.txt file is the first file that gets read and the Earth_Grass.psd image (specified in the text file) is the one used for the horizon when the program starts. If you wanted your panorama image to load first, give it a preload value of ‘Yes’ and name the text file so that it is listed first in alphanumeric order, such as Earth_00MyHorizon.txt.
<SN_VALUE name="ImageWidth" value="360.000000000000000000">
It's a panorama image; leave the value always as 360º.
Note: Both the image and text file must be in the Horizon Panoramas folder. You can give the text file any name.