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starView      Reference Sheet


starView is a novel learning tool that realistically models and visualizes stars from Hipparcos catalogue. It provides an interactive GUI to explore interstellar space.





Binaries and documents




1.       Put the "ImageReg" directory in the package under the starview directory such that this directory is at the same level as "bin", "data", and "scripts".

2.       Prepare your own ppm file of the sketch you want to use  e.g. “ImageReg/Images/orion_sketch.ppm”.

3.       Prepare the .aln file (alignment file) of the image e.g. “ImageReg/orion_sketch.aln” (the aln has a strict format - please use the above .aln, copy it to your own .aln file, and modify the "IMAGE").

4.       Start the starview program by “run” script and under Basic Adjustment -> Log10(m) space

               tune the scale to about 7.0 to make sure we are at the Earth's scale to look at the sky.

5.       Open the image registration panel and then the subpanel

                 [1. Open Alignment file]

               In the "Align File" edit box, type in “ImageReg/orion_sketch.aln”

                and click the "Load" button.

6.       Check the "show image" checkbox or press key '\' to show the image.  You may

               want to tune down the transparency of  the image to better see through the stars.




7.       In case you are using your own image (instead of the orion_sketch.aln that we have aligned already), you will see your own image mapped over orion, which is wrong of course.  Now open the subpanel

[2. Set Correspondence]

               You need to pick 3 stars in the star dataset and corresponds them to the image

(an image/tex coordinate) and the system can then compute a transformation

matrix from texture  coordinates to 3D coordinate.


8.       Now, the important steps:

-          Right click on a 3D star of your choice.

(You wil see the name of the star appears when the star is selected. You have to make

sure that this star appears in your sketch picture)

-          click on the "take star" button in the "set correspondence" subpanel

-          Repeat this two more times and take two more stars


9.       Now, you've selected three stars as the three 3D points in the space.  Next, you may

              press key "o" or check the "show image overlay" checkbox to bring up your picture

              on screen.  In the image overlay, you will see three green dots with numbers "1", "2",

              and "3" above the dots. These dots corresponds to the three stars your selected.

              Drag the dots to the corresponding stars over the image overlay to match the stars on

              your sketch image. You will see the 3D image starting to match the 3D stars accordingly.

              Note: you may drag the edge/corner of the image overlay to make it bigger.


10.    To fine tune the matching, you may use the texcoord spinners below the "take star" buttons.


11.    After you are satisfied with the alignment, you may export the .aln file (e.g. orion_sketch.aln) and you will see that your .aln is updated.  And inside the .aln file, you will find a matrix that transforms the 2D texture coordinate to the corresponding 3D position for you to put in your picture in 3D.


12.    As I know, even using the fine tuning in (13), you may not get the stars aligned well.  Because the three stars you selected are too close to each other in  the image and a small change in their tex.coord. will cause a big difference in the overall transformation.  You can pick another star, which is further away to the edge of your sketch and do (12) and (13) again for that star.  Repeat until you are satisfied and export the .aln file.



Note: If you want to get better result, the three selected stars are further away between each other.  The hint is that you can start with three stars in the middle of the pictures, and replace them (one at a time) by stars closer and closer to the edge of the sketch image. Later, if you want to improve the result, you may restart starview with the .aln you modified and polish the result.  You don't have to redo the whole process from the beginning. You have to make sure the space scale is 7.0 or at least a lot smaller than the star scale.

You may use right mouse button to pick a star and rotate view direction to look at a desired constellation. Or in the "star [p]icked or to pick" subpanel, type the first few characters of the constellation e.g. sco for Scorpios then click on the "look at star"

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