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floz

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  • "floz" started this thread

Posts: 109

Location: Uppsala, Sweden

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1

Monday, November 15th 2010, 3:26pm

Downsampling of cube faces in case of iPad?!

Hi there,

is it possible that the table_*.jpg files are downsampled when displayed (for iPads)?

I have 1280x1280px tablet cubefaces and they appear to get downsampled when shown (even zooming all the way in)...

Thanks for any insights on this,

Florian

floz

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  • "floz" started this thread

Posts: 109

Location: Uppsala, Sweden

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2

Monday, November 15th 2010, 4:04pm

Here's a screenshot comparing original table cube face with what's actually shown on the iPad:



There's a noticable loss in detail that does not get recovered even with zooming in a bit more . . .

3

Wednesday, November 17th 2010, 1:07pm

Hi,

yes, 1280px is unfortunately too large for a stable safari on the ipad,
by default images larger than 1024 will be downsampled to 1024 on the ipad,

you can try to disable that scaling with that code in the xml:

Source code

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<display html5rendermode="2" />

but in my tests it was near impossible to make a tour without crashing
with larger images...

best regards,
Klaus

floz

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  • "floz" started this thread

Posts: 109

Location: Uppsala, Sweden

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4

Wednesday, November 17th 2010, 1:11pm

Dear Klaus,

Thanks for your reply! So if I get you correctly, you recommend 1024x1024 tiles with html5rendermode set to 2?

Is this option documented anywhere, what does 2 correspond to?

Thanks!

Florian

5

Wednesday, November 17th 2010, 1:28pm

Hi,

no, the "html5rendermode" is an undocumented internal switch for testing,
with it there will be no downscaling, with it you should get the full 1280 pixels,
but the ipad safari browser would have a much bigger tend to crashing...

but when you use 1024px images, then there will be no downscaling (in any case),

best regards,
Klaus

6

Wednesday, November 17th 2010, 1:34pm

So which is better for viewing? 1280 downsampled or 1024? I know the smaller would download a tiny bit faster.

7

Wednesday, November 17th 2010, 1:42pm

Hi,

when you want the full control about the pixels then 1024 is better,
about better for viewing - ??? but in kind of loading speed there should be almost no difference...

best regards,
Klaus

floz

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  • "floz" started this thread

Posts: 109

Location: Uppsala, Sweden

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8

Wednesday, November 17th 2010, 4:02pm

Ok, thanks for that. One more quick question: Is there a similar downsampling happening for iPhones/iPoods? If so, what's the threshold there?

9

Wednesday, November 17th 2010, 4:06pm

Hi,

yes, for the iPhone/iPod 3 it's 600px and for the iPhone/iPod 4 800px at the moment,
I will document that more with the next release,

best regards,
Klaus

10

Thursday, November 18th 2010, 8:39am

Hello floz!

After reading your post, i've started testing (for the second time now...) what input-resolution gives the best rendered pano. I did this before with the krPano v1.0.8.11 because i couldn't find recommended sizes anywhere on krpano.com (by the way...i still can't... *confused* ).
So my first thougt was to use the natural resolution of the iPhone/iPod-display i am testing on. Therefor i have been using 480px and 960px cubes. The quality of the 960px cubes on a retina-display is pretty good so kept using it.
The 480px ones are an entirely different matter though...Altough the input picture looks good enough, the rendering-process of krPano makes them pretty blurry. So i tested with 560px and 640px for a screen resolution of 320x480px (normal iPhone/iPod3 res) and came to the conclusion, that 560px is the de facto best mixture between file size and quality.

Now Klaus says, that the new Version (krPano v1.0.8.12) downscales iPhone/iPod4 pics to 800px. So up to testing...
...
...
Outcome:
Using an input pic of 960px doesn't enhance the quality of the rendered pano much compared to giving it one with only 800px.
But setting <display html5rendermode="2" /> solves two things for me:
#1: the Qualtity gets significant better
#2: the loading time issue i posted in another thread is gone.

As for how often the safari keeps crashing now...still testing. But i made some changes within my app, so that i should be good for approximately 30 panos before the house comes down... *g*

Here are the zipped example pics...so that you know what i'm talking about...
(because of the file size (4 and 4.5 MB) i put them on our server...hope that's okay...)

http://www.diginetmedia.de/download/800px.zip
http://www.diginetmedia.de/download/960px.zip

On question remains though:
Why do the rendered pics get so blurry??? Just look at the original 800px cube and the Screenshot from the iPhone...ok, this is a 800px picture on a 960px screen. But using a 480px cube on a 480px screen, which should be best fitting (...), gets me the same result. In lack of screenshots you have to trust me on this one.

11

Friday, November 19th 2010, 10:06am

Hi,

do you mean why down sampling blurs the image a bit?
I think because internally the iOS is just using only a simple linear filter for downscaling,
a high quality downscaling filter (like lanczos) would be too slow,

best regards,
Klaus

12

Friday, November 19th 2010, 11:44am

No...what i mean is, why the by krPano rendered picture, when given a cube-pano-pic with 800x800px as input (so NO downscaling here), looks blurry???
Just look at the example pics within the earlier posted 800px.zip.
800px - 40%.jpg -> is the original
The others are screenshots made with different krPano versions and render modes. Do look at the grass. In the original its pretty sharp. In the rendered ones it is blurry.

I hope i could illustrated it a bit more.

Oh and by the way...of course i do also test on iPads (iOS3.2 and iOS4.2GM). But not with the krPano...not yet that is... ;-)

13

Wednesday, November 24th 2010, 4:57pm

Hi,

I think that what you mean is the normal effect of the 3d distortion and the bilinear interpolation of the pixels,

best regards,
Klaus

HansNyb

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14

Sunday, November 28th 2010, 5:35pm

I am confused about this maximum size.
Do you mean that Safari it self is downsizing the cubefaces or is KRPano doing it.

I can see that PangeaVR also uses 1024x1024 but I recently delivered 2048x2048 for an iPad application for a large US university.

They asked for that size even if I recommended smaller.
I also know that Eric Leemann has been using Pano2VR HTML5 in 2000x2000 for his iPad.

Hans

15

Wednesday, December 1st 2010, 12:08pm

Hi,
I am confused about this maximum size.
Do you mean that Safari it self is downsizing the cubefaces or is KRPano doing it.
by default (that means without the 'html5rendermode=2' setting) krpano is downsampling the images to
provide a most stable usage and control of the result,

it's possible to draw an 3d distorted image in several ways, e.g. when using the setting html5rendermode=2
a other way is used, then krpano will not resize anything, then Safari has the control over it and it some cases
it seems that it does some kind of mipmapping, that means it uses automatically downscaled images,
then the result can be much more blur,


I can see that PangeaVR also uses 1024x1024 but I recently delivered 2048x2048 for an iPad application for a large US university.
PangeaVR is an App, that's something completely different,
in the most cases OpenGL will be used there for rendering, and with that the App has full more control about the imagesize and the used memory,


They asked for that size even if I recommended smaller.
I also know that Eric Leemann has been using Pano2VR HTML5 in 2000x2000 for his iPad.
and you have seen the full 2000x2000px resolution on the iPad? do you have a link?
I personllay wasn't able to show/load a pano with real displayed 2000x2000px without crashing Safari on the iPad,

best regards,
Klaus

HansNyb

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16

Wednesday, December 1st 2010, 12:36pm

I do not think he has anything online. He uses it with Goodreader.
It was a discussion at PanotoolsNG but it seems that he later found out that what ever larger than 1066 cubefaces he uses they are downsized by iPad.
Found this thread at Pano2VR
http://gardengnomesoftware.com/forum/vie…lit=iPad#p20967

I have done some tests and if the max is 1024 you have to set the default MFOV to around 100 to see it in a decent quality.
Currently the Tools set it to 90 which already is a large wide angle view.
My tests show that MFOV 100 on 1024x768 corresponds to a vertical FOV of 85 which is pixel to pixel with 1024x1024 cubefaces.

Also I can see that the maxfov does not work the same on HTML5. MaxFov 1 will give you around 1.5 on the HTML5. The tools default is 1.5 and you can actually zoom in to 50 VFOV on HTML5 which is very blurry.

Hans

17

Wednesday, December 1st 2010, 1:24pm

Hi,
Also I can see that the maxfov does not work the same on HTML5. MaxFov 1 will give you around 1.5 on the HTML5. The tools default is 1.5 and you can actually zoom in to 50 VFOV on HTML5 which is very blurry.
do you mean the "maxpixeelzoom" setting?
right, this is currently not supported and will be ignored in krpanoJS,
the normal "fovmin" setting will be used for the minimum fov value,

best regards,
Klaus

HansNyb

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18

Wednesday, December 1st 2010, 1:30pm

the normal "fovmin" setting will be used for the minimum fov value,


So it is the default fovmin setting I see as the max zoom.
Can you set a special fovmin for the iPad/iPhone using the device attribut?

Hans

19

Wednesday, December 1st 2010, 1:38pm

Yes, it's the default fovmin, which is 50 in krpanoJS,

there no automatic alternative fovmin setting at the moment,
but there are the following possiblites:

use a maxpixelzoom setting for Flash and a fovmin setting for krpanoJS,
when maxpixelzoom is defined the fovmin will be ignored in Flash,

or:

set the fovmin dynamically in an event,
e.g. in the onstart event:

Source code

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<krpano onstart="start();">

<action name="start">
  <!-- e.g. just for the iphone -->
  if(isphone, set(view.fovmin, 60));

  <!-- or all html5 views -->
  if(ishtml5, set(view.fovmin, 60));

  <!-- or a different fovmin for each device -->
  if(isphone, set(view.fovmin, 50));
  if(ispad, set(view.fovmin, 60));
</action>


best regards,
Klaus

HansNyb

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20

Wednesday, December 1st 2010, 2:06pm

Thanks I suppose that you should be able to preview that in Safari.

I just tried to preview the devices settings but that does not work.
If I set devices="desktop" in a button plugin it shows up also using iPhone or iPad as useragent.
And if I set it to ipad it does not show up with any agent. What works is if I use devices="flash"

What I actually want is to exclude navigation buttons for the iPhone 3 which has a very small resolution but that seems not to be possible with any of the device settings.

I suppose that has to be a different xml and a sniffer in the html based on resolution.

Hans