Beta 3 Muti-resolution gives blurry results

[Judy-A]

I did a test multi-res output and am unpleasantly surprised at blurry results. The pano seems to move in and out of focus as one zooms.

When a P2VR multi-res pano is displayed, does the Flash enlarge the lowest possible resolution tiles until it needs higher-res tile? If this is the strategy, then a pano will be blurry most of the time and sharp only when the viewer's zoom level lands exactly on the resolution of a level.

For my purposes, where I value sharpness over a speedy download, I would much prefer that larger tiles be scaled down.

For comparison, you can view my test files, both made from the same equirectangular image, and both with largest cube face set to 2096 pixels.

Multi-resolution (output settings in web page):

http://www.judyarndt.ca/tests/p2vr_mult ... tires.html

Single resolution:

http://www.judyarndt.ca/tests/p2vr_mult ... leres.html

The same pano is in my recent 'Alberta Badlands' gallery, bottom left, as a single resolution, 2100 cube-face file that will open in a fullscreen HTML window.

http://www.judyarndt.ca/galleries/badla ... t2010.html

Judy Arndt

Mac Pro, Mac OS 10.6.4
P2VR 3.0beta 64bit
Revision 1502/4.6.2 (Aug 1 2010, 03:40:24)

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Edit: New problem. The multi-res version posted above does not appear to be finding the non-embedded tiles. I've emptied my browser cache. I uploaded, to my server, all the files and the folder of tiles exactly as shown in the video tutorial.

[wigi]

I did a test multi-res output and am unpleasantly surprised at blurry results. The pano seems to move in and out of focus as one zooms.

When a P2VR multi-res pano is displayed, does the Flash enlarge the lowest possible resolution tiles until it needs higher-res tile? If this is the strategy, then a pano will be blurry most of the time and sharp only when the viewer's zoom level lands exactly on the resolution of a level.

This is true, it is bad strategy - therefore pano is blurred. I hope that Thomas will improve Multiresolution in next version.

[smooth]

Hi Judy,

As I told you to try this out to improve your display results I feel somewhat obligated to help.
Since then though, I have found some worrying problems as you can read in this thread.

As for the blurriness, I would suggest that your smallest tiles be that of "normal" panorama that you or I would built where the smallest tiles are still over 1600 pixels and your maximum maybe higher than what you would normally offer. Again see the thread I mentioned and look to the tiles sizes I'm using.

We want to start with good and get better with zooming. Not start with rubbish resolution and wait for better to arrive!

Regards, Smooth

[smooth]

Judy,

Please try the following settings:

Level Tile Size 388

3104
2328 Load at start up
1552 Embedded

or
Level Tile Size 485

3104
2666 Load at start up
1890 Embedded

These settings are based on your 9758 pixel panorama image.
Of course you can always remove the 3104 tile set if you feel they are too large.
Also remember to limit the zoom Min FOV so you cannot over zoom in. But you still want the full size (max) tile to load.
I tested this by numbering a the same tile position for each zoom level.

Regards, Smooth

[Hopki]

Hi Smooth
Can I ask how you get to these figures?
Just curious, also I totally agree with load good and get better.
Hopki

[smooth]

Hi Smooth
Can I ask how you get to these figures?
Just curious, also I totally agree with load good and get better.
Hopki

1) Know the size (width) of the original equirectangular image = 9758 pixels
2) Divide it by Pi = 3106.15947795639
3) Divide Pi by 8 and drop the excess = 388.25
4) Multiply the clean full number by 8 = 388x8 = 3104
5) Use that figure as your maximum cube size = 3104
6) Divide the maximum into quarters = 3104 divided by 4 = 776
7) 1/2 of the maximum becomes the smallest tile size 3104 divided by 2 = 1552 (*so long as it falls within your required starting clarity)
8.) 1/2 the size difference between the smallest and largest added to the smallest tile becomes the 3/4 tile size. 3104-1552 divided by 2 = 776. 1552+776 = 2328

*If it doesn't find another number that is multiple x 8 to give your a required size and adjust the 3/4 tile to match the same 1/2 way mark between smallest and largest.
I.E: 242x8 = 1936 (new larger small tile) as apposed to 194x8=1552. 3104-1936 = 1168. 1168 divided by 2 = 584. 1936+584 = 2520 (New larger 3/4 tile)
I'm working on the fact that all tile faces should be dividable by 8 as this keeps all the tiles 1:1 aspect ratio "square" which is true to the first example (not so much to the second because I must have confused myself). It should read:

Level Tile Size 484

3104
2520 Load at start up
1936 Embedded

The "Level Tile Size" is simply the starting (smallest) tile divided by 4.

I don't know if there is any science behind this or even if it is correct but it's what I came up with and I can't find a hole in the theory.
Seeing as this doesn't come with any instructions I had to make up my own.
Maybe I'm just p'ing into the wind!

Regards, Smooth

[Hopki]

Thanks Smooth, I was just trying to work out the last one.
Which of course I couldn’t. but did not know if I was missing something.
all the best
Hopki

[Judy-A]

Level Tile Size 484

3104
2520 Load at start up
1936 Embedded

Hi Smooth,

My test file this time was the Orkney Lookout Pano which at cube face 2100/quality 50% (2.9 MB) has JPEG banding in the clear blue sky. The original is here:

http://www.judyarndt.ca/pano-sept2010/r ... y_med.html

I tried your suggested output sizes, and the result displays with good, but not better, sharpness. There is less banding in the sky, but it hasn't been eliminated.

The disadvantage of using these settings is that the multi-res SWF file size is now 4.7 MB (compared to 2.9 MB). The folder of tiles adds a whopping 23.4 MB of extra files I would have to manage and upload to my server.

I was interested in multi-res because I'd been thinking of embedding small panos (~400 x 200 pixels) in a web page to serve as previews, and then let the user click the fullscreen button to view the larger pano. I would perhaps be better off using two SWF files linked in a tour.

I'm thinking the multi-res feature is not aimed at images like my fisheye landscape panos, but at gigapan images like the one of Nottingham High School which Stalwart just posted.

Judy

[DemonDuck]

I won't speak to the other issues but banding is purely the result of the high degree of compression.

My own personal preference is about 80% to 85% on the quality setting -- bigger files but no banding.

Also, there exist jpeg compression optimizers that do a very good job at finding the best compression level for a given photograph (pano) I had one for a while and it worked very well. Then I stopped caring about how big the pano download was

[smooth]

Yup, that's pretty much it. You can't compress the images that far and not expect horrendous banding.
It is amplified with the added saturation to blue up the sky. As I stated on the Panoguide forum dropping below 75 compression will introduce banding.

Your target should be to produce a starting panorama with no banding, good clarity and within 1/2 a megabyte to your original.
Downloading 3.5mb as apposed to 3.0mb I feel is acceptable compromise if it is to rid the panorama of banding.
Did you change the interpolation setting as I advised also?

I agree that adding another 20 or 30 megabytes to the server in extra tiles may be too much and in this case you would remove the 3104 tile set from the project.
But server space now is cheap or unlimited with decent hosting providers so does it really matter how many megabytes are on the server? The viewer will only call upon these tiles if they zoom right in and only the tiles relevant to the part of the panorama on screen in view.

Anyway, it was only an attempt to help you out. I wouldn't be happy showing all that banding just to meet a compromise to a download target size.

Regards, Smooth

[smooth]

I would perhaps be better off using two SWF files linked in a tour.

Yes, that is an option. One I have used many times before and if you use the target of $cur you can keep the same view on click to help keep it seamless as far as view is concerned.

Regards, Smooth

[erik leeman]

A perhaps often overlooked possibility to reduce banding in clear skies is applying individual quality settings (= compression ratios) to your cube faces.

To do this:
In the 'Flash Output' menu, select the 'Settings' tab, then in 'Tile Settings' section click on the 'Tile Quality' button.
A 'Cube Face Quality' menu will then pop up.
Select the tick-boxes for the Up and Down cube faces and set the quality you'd like them to have.
Good values for clear skies and uninteresting (just dirt) nadirs are 90 for the Up-face, and about 60 or less for the Down-face.

Because of the absence of detail in the sky-filled Up-face it will still be very small in kB in spite of this high quality setting of 90, whereas the detail-saturated Down-face will remain relatively large (in kB) in spite of the high compression at 60. That's how JPEG compression works.

Of course the part of the sky that's visible in the horizontal row of cube faces will still show banding if you set their quality too low, but often this is not too much of a problem.
In the finished Flash output you won't be able to see a sudden change in quality if you keep the quality values reasonably close to each other, say 60-80-90.

Cheers!

Erik

[smooth]

That is a good point Erik, only I don't understand how or if this works when your producing multi-res tiles.
Lets say it does, does it only effect the embedded tile set/s or all the tiles across the tile sets. Obviously you wouldn't necessarily want to compress your higher detail tiles like you would the starting set.
This is the problem when we haven't been explained the operating procedure of the software.

Do you know how it works? Maybe Thomas might like to explain?

Regards, Smooth

[Hopki]

Just to confirm, if you set the tile quality in the main flash project window, this will affect all tiles even in multi res.

@Smooth
I think your comments are spot on and have added tile quality settings in multi res to the wish list.

[smooth]

Just to confirm, if you set the tile quality in the main flash project window, this will affect all tiles even in multi res.

I was afraid of that.

@Smooth
I think your comments are spot on and have added tile quality settings in multi res to the wish list.

OK, great. Separate compression for each tile set (level) is desirable. Consideration should be given also for these extra tile sets (levels) for the use a individual cube faces as Erik was pointing out.

I really want to see the "pre-loader" tracks enabled with Multi Resolution also.

Regards, Smooth