Star Tracer Tip

Discussion forum for Tawbaware's Star Tracer and Image Stacker software
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ranord
Posts: 4
Joined: Wed May 11, 2011 8:24 am

Star Tracer Tip

Post by ranord » Wed May 11, 2011 8:36 am

Hi,

I'm new to Star Tracer and getting quite frustrated getting acceptable star lines.

I did my first trace with a JPG and was able to get a rather accurate trace rather quickly.

Now I'm trying to trace using an 8-bit TIFF and for the live of me I can't get an acceptable result. I've carefully added 30 lines and it still complains to me. So what other guidelines do you have other than what is in the help doc.

Should the lines be all the same length, in the same arc, on separate arcs, close together, spread far apart like over the whole image, long better than short. I feel like I'm wasting alot of time trying to figure out what the program is really looking for.

Also why does Star Tracer disappear after I optimize requiring me to swap screens to get it back, that's really irritating.

This would be a cool program if I could only get it to predictably work.

Thanks

Roger

maxlyons
Posts: 3649
Joined: Fri Jun 20, 2003 8:55 pm
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Re: Star Tracer Tip

Post by maxlyons » Wed May 11, 2011 8:57 am

ranord wrote:I can't get an acceptable result. I've carefully added 30 lines and it still complains to me.
Can you provide more detail on these "complaints"?

Max

ranord
Posts: 4
Joined: Wed May 11, 2011 8:24 am

Re: Star Tracer Tip

Post by ranord » Wed May 11, 2011 12:56 pm

Sure Max.

I'm at work so I don't have the exact message but I get a popup message basically telling me I have some improperly places star lines. When looking at the star lines I entered and the number next to them I see wildly varying numbers. Usually the best, lowest, is around 1 with the highest numbers in the 30s or 40s or 50s. I try addling more lines or removing the worse line but that doesn't seem to help.

So I'm wondering what I'm doing wrong. I've tried fewer lines and longer start lines. I'm estimating the FOV at 50 and have not selected any other options for the optimizer to use, just the default ones.

I can give you the exact message I'm getting later tonight if that helps.

Thanks

Roger

maxlyons
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Joined: Fri Jun 20, 2003 8:55 pm
Location: USA
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Re: Star Tracer Tip

Post by maxlyons » Wed May 11, 2011 11:10 pm

ranord wrote:I'm at work so I don't have the exact message but I get a popup message basically telling me I have some improperly places star lines.
My guess is that you either have improperly placed star lines, or you have incorrectly specified something (most likely FOV). If you tell Star Tracer that the FOV is 50 degrees, and the correct value is something else, then you'll end up with large optimization errors which Star Tracer interprets as improperly placed star lines. Star Tracer can't work out what you've incorrectly specified, but that error message is most likely a result of something that has been incorrectly specified (e.g. FOV, projection, star-lines, etc.). Try optimizing FOV and see what happens.

Max

ranord
Posts: 4
Joined: Wed May 11, 2011 8:24 am

Re: Star Tracer Tip

Post by ranord » Thu May 12, 2011 12:18 am

You hit it squarely on the head Max. I admit I am improperly placing the star trails, that exactly what the *** Warning and Hints *** message is telling me and I quote

1.11 lines have very large optimized distances...either the lines are
misplaced, or the image properties are incorrect
*** Project parameter Summary ***
Pitch,Roll: 48.9 -71.7
Distortion (a,b,c) 0.000 0.000 0.000
Shift (d,e):) 0
Field of View: 50.0
Avg/Max line dist: 7.7(!) 42.6(!)

The focal length of the lens is 39mm therefore according to the FOV calculator on your site the FOV is 49.6, I rounded to 50

I aligned the ends of the star lines in the center of the star trail, don't know how to get more precise. I have 24 lines drawn.

So given that I have misplaced lines what is your suggestion to get a proper fitting??? I'm not trying to say there is anything wrong with the program I just would like to know it's ways.

maxlyons
Posts: 3649
Joined: Fri Jun 20, 2003 8:55 pm
Location: USA
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Re: Star Tracer Tip

Post by maxlyons » Thu May 12, 2011 8:45 am

ranord wrote:I admit I am improperly placing the star trails
Maybe, but maybe not.
11 lines have very large optimized distances...either the lines are
misplaced, or the image properties are incorrect
It is just as likely that you have incorrectly specified something ("image properties are incorrect"). My first guess is FOV. Is your image in portrait orientation? Has it been cropped? Are you using a crop-sensor (i.e. not "full-frame") camera? If any of these are true, then the value of 50 you entered is incorrect. I suggest trying to optimize FOV.

Max

ranord
Posts: 4
Joined: Wed May 11, 2011 8:24 am

Re: Star Tracer Tip

Post by ranord » Thu May 12, 2011 11:41 pm

Max,

I tried optimizing FOV and it worked out much better, after removing lines so I didn't get the warning message anymore. I made the images with a 5DII using at 17-40 lens at 39mm, according to EXIF data, and did not crop the image. I also applied lens correction in Lightroom before exporting. I combined 6 images in Image Stacker prior to Star Tracer. I'm sure there is a learning curve involved and eventually I'll get it down.

Roger

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