Missing stars even when the magnitude filter should pass it

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Topic author
tec
Posts: 51
Joined: 14.03.2006
With us: 18 years 8 months
Location: Huntsville, AL

Missing stars even when the magnitude filter should pass it

Post #1by tec » 30.06.2006, 22:17

I have noticed that there are several stars that are not drawn when I adjust the magnitude filter. But the apparent magnitude is smaller than the filter using the [] keys. I am using points as the star style. Here is an example.

Only render stars and center star HIP 1099. Adjust the star magnitude filter to 8.5 and you can see 1099. Use the [] keys to lower the magnitude threshold and watch for 1099 to disappear. It will disappear when the filter is at 7.9 but the star has an apparent brightness of 6.14. Why did it disappear?

There are several others that I have noticed doing this same thing. They are 46768, 25708, 82898, 93543, 37843.

The reason this is a problem is because I am reading the screen pixels and running the image through my star browser pattern matching algorithm. My algorithm blows up when I center on these stars because it is not there.

Thanks
Tim

Topic author
tec
Posts: 51
Joined: 14.03.2006
With us: 18 years 8 months
Location: Huntsville, AL

Celestia is missing stars but they are in the star database.

Post #2by tec » 05.07.2006, 15:55

Here is somemore information about my problem. I am in staroctree::processVisibleObjects() and I place an if statement in the for loop after the code:

Star& obj = _firstObject[i];

if( obj.getCatalogNumber() == 46768 )
ii=0;

I placed a stop at the ii=0; I was hoping to catch the star rendering so I can track the problem area. For some odd reason processVisibleObjects never attempts to render this star. I don't understand why. It is part of the starDB. I need to find out why this star is filter out because it is not rendering. It should render becuase it's apparent magnitude is 6.114 and my filter is 6.5. Can someone show me how this star is filtered? I have a feeling this problem is some kind of round off error.

Tim

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selden
Developer
Posts: 10192
Joined: 04.09.2002
With us: 22 years 2 months
Location: NY, USA

Post #3by selden » 05.07.2006, 17:06

As Chris mentioned when he responded to your similar posting in Bugs forum, this is a bug which he'll be investigating.

(I'll move this to the Bugs forum and try to join it to the other thread. There's no need to create multiple discussions describing the same thing.)
Selden


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