Scan Size Calculation Problem

[White-Light]

Hi,

I'm having some trouble calculating and adjusting scan size so would appreciate some help.

I've had some tails on some displayed patterns and although the scanners aren't complaining I'm suspecting scan angle problems.

So I decided to use the angle calculator off here to calculate the angle.

The problem is I'm getting a ridiculous result and so wondering if I'm doing something wrong.

The distance laser to wall is 274cm

The Test Pattern displays at 60cm square - calculator says square units so = 3600 units squared (? (60x60) correct figure used or should it be 60)

According to the scan angle calculator that gives a scan angle of 162.69 degrees

Yet the pattern on the wall doesn't look very wide at all and the scanners aren't complaining and displaying a perfect ILDA test pattern. I reckon you wouldn't even see it at 7 degrees at that rate.

I'm presuming I'm doing something wrong here therefore.

Anyone help?

[Jem]

Hi Al

Rob used to do a scanangle chart, may even have been available as a .pdf

This takes all the hard work out fo calculating scan angles. You basically put it at a set distance from your projector and adjust your image to fit one of the pre-drawn squares on the chart. This then tells you the exact scan angle without the measurements.

I've had a look for it on Rob's website but it doesn't appear to be there. I know he was giving these away at one of the early LEM's, perhaps you could drop him an email.

Have you had a look at the software settings, things such as line anchors and visible line settings. Adjusting these may possibly help.

I'm sure I have a chart here somewhere if you're unable to get one, just let me know and i'll have a hunt for it.

Cheers

Jem

[Banthai]

Rob posted this many moon Lumens ago....

i hgave always found this helpfull

make sure when you print it out that the line at the right is 10cm long this will make sure its the right scale
them place the printout at 30cm from galvo mirrors

and bobs ya uncle ... or better "Stans" ya uncle


scananglechart[1].pdfscananglechart[1].pdf

all the best ...

Karl

[Banthai]

bloody hell jem ... we must be typing in stereo

[White-Light]

Hi Jem,

I've got the pdf but unfortunately it requires A3 paper and my printer is A4.

I'm also scared of setting it on fire from 30cms. I'm burning wood in under 1 sec from 10 metres, albeit with a pencil rather than modulated beam.

I know everybody raved about this calculator so it should work but clearly something is going wrong. I can't see my LM's displaying a perfect ILDA test pattern at 162 degrees or any pattern at all. Problem is I'm not sure where I've gone wrong, probably something simple but...

[Banthai]

Im guessing that you have doubled the scan angle +/- 81 degs

im sure it wont be 162 deg as that would be near impossible for the scanners thats nearly half a semi circle

Karl

[White-Light]

BTW Karl thanks for putting the pdf up we cross posted.

[White-Light]

They're rated for ILDA test pattern at 7 degrees and 30K.

That's why I can't understand how ilda test pattern can display if its 162 degrees plus it doesn't look very wide on the wall. Confused.

[Banthai]

No Probs ... seems like me you and Jem are getting our "saturday afternoon internet time"

im guessing that the angle you are getting is half ... +/- 40.5 deg...... total 81 deg .....

Be carefull as that is a high angle and will make the scanners work very hard

[Banthai]

if you print off Robs scan angle with no scaling .... it should print the left hand side on an A4 sheet .... then you can print off a second copy turn it round and selloptape them together
if you are using the test pattern which will be scanned .... ther is very little chance of it catching fire .... unless you are doing this on a Laserscope

Karl

[White-Light]

Thank Karl.

Until you said you'd done it I didn't realise it could be done - it couldn't in my version of Acrobat but I found out that if I upgraded to Acrobat X then it could be tiled.

Now done.

[Banthai]

Dont keep us in suspenders buddy ...

Let us know what the actual angle was when you find out ..... I wont sleep tonight otherwise

Karl

[Jem]

Isn't it nice when we all work together

I have an A3 colour printer at the office Al. If you want I can print a few copies out... might even be able to find something fire resistant

As Karl says though, the chance of setting fire to anything once you're scanning is pretty remote.

As for 'Saturday afternoon internet time', it's more a case of every time i'm passing my computer I take a quick sneeky peek, just long enough so that I can 'catch up' without being accused of wasting time

Cheers

Jem

[White-Light]

OK sanity check.

What are you guys running in Beyond?

I've found that 8 degrees = 12 on X axis and 12 on Y axis in the Scan size settings under "Settings".

This seems ridiculously small but appears to match the chart from 30 cm.

Yes please on the printing Jem. My art skills are sadly lacking even when it comes to sticking things together!

[White-Light]

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[Banthai]

The Beyond settings are based on the standard 0 to 5v signal for a standard set of scanners ..... but each set of scanners are tuned slightly differently .... so i think that your Gain setting on the glavo amps will be set a bit lower .... which will give you the reduced angle .......
at the end of the day what you are seeing on the test sheet is what you are actually getting ... the software setting will be a rough guess .... you could if you wanted ... re-tune the scanners so they give 12 degs when beyond is set to 12 degs .... but its really not worth it

Karl

[stanwax]

For information the chart has always been available on my download page - 2 clicks from my home page will get you the chart.

What are you guys running in Beyond?

I've found that 8 degrees = 12 on X axis and 12 on Y axis in the Scan size settings under "Settings".

Always bear in mind that the value you are refering to cannot be compared to other projectors hence why no software can ever have an X & Y scale calibrated in degrees. It depends on the physical capabilities of the scanners and their driver settings to be able to convert a given voltage from the DAC to an angular movement of the scanner motor.
If using the software correctly you should not be adjusting the scan scale in the projector settings - I ALWAYS run this value at 100%.
Rob

[White-Light]

If using the software correctly you should not be adjusting the scan scale in the projector settings - I ALWAYS run this value at 100%.
Rob

OK now I'm really confused.

By default Beyond has the sizes set to X=50 y=50. When I use your chart this equates to around 15 degrees yet the Kvant web site quotes for LM's:

Scanning angle: 80° for both axes Scanrate: min.30kpps* *Measured at 7° scanning angle and Pangolin test frame Laser media with 5% /±0.5%/ shape distortion. Mirror size designed for 5mm laser apertures.

So shouldn't I have set 7 or 8 degrees for 30k scanning?

[norty303]

So shouldn't I have set 7 or 8 degrees for 30k scanning?

Your beam shows will look crap if you do...

Use the specific projection zones to set the size, depending on what you are doing (graphics, beams, overhead effects, etc)
Hint: you don't project the ILDA test pattern in 'most' gig situations

I can honestly say I've never once done any calculations for scan angle. I just know that from experience, roughly how wide I can scan certain effects. e.g. tighter for graphics, very wide for beams. The only adjustments I've ever made to my scanners has been to have the gain equal on my matched pair of projectors.

[stanwax]

You should scan at a size that is appropriate for the venue you are using. If I went into a club and scanned at 8 degrees I would not be able to do anything much that would impress.
Important: Understand this. The angle of 8 degrees (or 7 or what ever) is to allow 2 projectors similarly tuned to display a given graphic and allow it to display identically. Some jobs will require small angles like this but most occasions you will scan *much* wider.

I will be surprised if the scanners will reach 80 Degrees in reality - DTs (not the wides) will do about 50 (60 at a push) degrees but the scan will fall of f the Y mirror before it reaches these values.

As for the 100% setting in the projector settings - this is the setting that determines the Max overall size the scanners will ever be able to use and this applies to all projection zones. Learn how to use zones and you will understand why I use this value set so high.

Rob

[Banthai]

For best performance ... yes ( depending on your scanners )
8 degs is optimum for 30k scanning images
although i dont have Beyond as i only have Qm2000 with livepro ... but the settings in my Pangolin of 0 to 100 equate to the DAC voltage output 0 to 5 volts

Karl

[White-Light]

Rob, how do you determine the limits?

Looking for distortion then backing off a little?

[stanwax]

Al
I do beam shows. I never do graphics cos I dont like them (too much edam) and think they are very outdated and the power of video projection far exceeds laser graphics, so my beam world will be very different to a graphics world. The exception is logo or text projection but they will never be scanned wide anyway unless I have to be 3 feet from the termination!
In beams I run 30 or 40k scanners at 18-20k. That way they can scan wide without having to defy the laws of physics. Its better visually (as long as you dont have too many points - but then again I use this to advantage) and it means the scanners will last for more than 2 shows.
For beams it really does not matter if corners are a little rounded or the circles are not perfect - the effect is in the air not on a wall.
Like I said understand zones and dont dwell on things like actual scan angle and you will do yourself a huge favour.
Rob
Rob

[laserist]

Hi,

The distance laser to wall is 274cm

The Test Pattern displays at 60cm square

I looked but didn't see the answer, so:

arctan(30/274)*2=12.5 degrees

brian

[White-Light]

Hi Brian,

Many thanks.

Seems I'm either doing something wrong with the scan angle calculator or it works incorrectly.

Anyway, if anyone needs one, I've now found one online that came to the same result as you:

http://www.diodelaserconcepts.com/ph...lator.php?m=fa

Interestingly enough Rob I found out why I couldn't set different angles in different zones in Beyond, there was a bug. Alexey has now fixed it for the next build.