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JMM
Experienced
Topic Author
Posts: 158
Joined: 02 Aug 2021, 11:18

Trying to comprehend why Zoom is not working in X3 for my Equirectangular images

29 Dec 2022, 01:48

Hello, Karl,

For days I've been looking at THIS thread, where you tried to explain why Zooming was not possible for that user, but unfortunately I can not understand what you were explaining... the part about:
X3 will zoom all panoramas as long as it does not scale beyond pixel-resolution.
Situation:
HERE is a link to my original (source) image, as an example.  Once the page opens, if you pan your view 90° to the right so that you're looking up that street (with the Esso station on the left), notice that you can zoom in all the way to those 2 houses on the top of the hill, above the trees.

I downloaded that equirectangular image using a program called Street View Download 360.  Once that JPG image is saved on my PC, I can at any time open that image using Street View Download 360, and successfully zoom all the way in to those 2 houses on that hill.

You can see that same (downloaded) equirectangular image HERE on my X3 website.  When you pan that image on my site 90° to the right so that you're looking up that street (with the Esso station on the left), notice that you can barely zoom in all, maybe only 1' at most.

The only thing different, between the source image & my equirectangular image on my X3 site, is that the image on my X3 site has the Exif information stripped from it.  However, if I start up my Street View Download 360 program, then tell the program to open up that same image on my X3 site, I can zoom in all the way to those 2 houses on the hill, so there is nothing wrong with that equirectangular image on my X3 site.

Which brings me back to your explanation of
X3 will zoom all panoramas as long as it does not scale beyond pixel-resolution.
Can you please clarify that reason... especially the party about
as long as it does not scale beyond pixel-resolution
Much appreciated in advance for any further explanation (clarification) that you can provide me with.

Thank you & have a great day.

Regards,
John
Location: Burlington (Toronto-ish), Ontario, Canada
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mjau-mjau
X3 Wizard
Posts: 14010
Joined: 30 Sep 2006, 03:37

Re: Trying to comprehend why Zoom is not working in X3 for my Equirectangular images

29 Dec 2022, 05:19

Ok :) Let me explain a bit more ...
JMM wrote: HERE is a link to my original (source) image, as an example.  Once the page opens, if you pan your view 90° to the right so that you're looking up that street (with the Esso station on the left), notice that you can zoom in all the way to those 2 houses on the top of the hill, above the trees.
First of all though, let it be noted that the above is not the same source as the one you have in your X3 gallery. The Google view uses a "cubic" source (multiple tiles), ultimately in higher resolution than the single-file equirectangular source you are using in X3 ...
JMM wrote:
X3 will zoom all panoramas as long as it does not scale beyond pixel-resolution.
Can you please clarify that reason... especially the party about
as long as it does not scale beyond pixel-resolution
So let's just do some quick math here ... The original source is 13312 px. Let's say 1/4 of the image width is visible on screen (just an approximation, as it depends on screen aspect, distortion) ... 13312/4 = 3328 px. I'm on a Macbook 14" (retina) screen 3024 x 1984 px ... So that leaves around 3328px to display on 3024px screen area ... 3328/3024 = 1.1. So on my screen, I get a tiny zoom amount around 10%. On a larger/taller screen than mine, you will probably have NO zoom. If you were able to zoom past the "pixel" level, there is no more "detail", and we are just upscaling pixels (which then returns a blurry result).

Does this make more sense? I'm not sure how you get the "source" from Google maps, but it just creates a "snapshot" in high resolution, but doesn't include the massive data used in Google. Even if it did, this could not be in single-file "equirectangular" format.
 
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JMM
Experienced
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Posts: 158
Joined: 02 Aug 2021, 11:18

Re: Trying to comprehend why Zoom is not working in X3 for my Equirectangular images

29 Dec 2022, 06:06

First of all though, let it be noted that the above is not the same source as the one you have in your X3 gallery. The Google view uses a "cubic" source (multiple tiles), ultimately in higher resolution than the single-file equirectangular source you are using in X3 ...
That explains it.  I assumed, because the downloaded file was in the shape of a sinewave, that it was single-file equirectangular.  I stand corrected, thank you.  And as X3 does not handle "cubic" images, I'm out of luck.  I understand now.

And as for your quick math, although I have a 4K monitor, I have it set at 200%, so 1080p (1920*1080).  In my case, that would be 3328/1920 = about 1.73 that I could zoom in, maybe slightly more than on your screen, but not by much.

As a test, to confirm that I actually understand your explanation  :slight_smile:, I temporarily set my monitor's resolution to 720p (1280*720), and sure enough, I could zoom in quite a bit, as you implied, although of course the image was not as clear at that lower resolution, understandably.

Thank you for clearing that up, and explaining it quite well, I might add.

I thought that maybe the problem was on my end, with me perhaps missing a setting in X3, or something like that.

Much appreciated, Karl, for taking the time to explain it.

Have yourself a splendid day.
Location: Burlington (Toronto-ish), Ontario, Canada
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mjau-mjau
X3 Wizard
Posts: 14010
Joined: 30 Sep 2006, 03:37

Re: Trying to comprehend why Zoom is not working in X3 for my Equirectangular images

29 Dec 2022, 20:31

JMM wrote:And as X3 does not handle "cubic" images, I'm out of luck.
X3 does support "cubic" tiled panoramas, for example created from Marzipano Tools:
https://www.marzipano.net/tool/

Example (you might even notice that "tiles" get loaded)
https://demo.photo.gallery/examples/plu ... -in-bruges

The point of cubic panorama compared to single-file equirectangular, is that it can handle larger resolutions, and image data will load in progressively. It is not as convenient as equirectangular panoramas of course.
JMM wrote:And as for your quick math, although I have a 4K monitor, I have it set at 200%, so 1080p (1920*1080).  In my case, that would be 3328/1920 = about 1.73 that I could zoom in, maybe slightly more than on your screen, but not by much.
That's not quite right. A screen will always have the same amount if pixels, regardless of "zoom" level. 4K would always be ~ 4000 px wide ... "zoom" only scales the elements so that they are good viewing size for the viewer. Any images on screen will always take advantage of the screens pixel resolution, regardless of any zoom. When you have "pixel doubling" on your 4K screen, it's only to adjust the general size of everything, but the quality of your screen still retains the capability of rendering high-res images across all ~4000 px ... Therefore, images always display across "pixels".

When you set your monitor to display as a different resolution than the native screen resolution, you are only setting it to "display like" the other resolution. True pixels always remain the same.