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WhisperingPond

Large Images, Photos, Posters

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My search for answers to this question always leads to the size limitations for uploading an image to SL. At the same time I've seen galleries and shops with huge images & artwork. Are they created as mesh objects first?

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One option is to upload your image in parts.  For example, you could split your image into 4 equally sized parts, each 1024x1024  Then upload each separately, place each on a large prim, and arrange the prims so that you once again have what looks like a single image.  

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The largest upload is 2018 which becomes a 1024 texture.  Mesh has nothing to do with it and most large photos or art are on a simple prim or a mesh cube.  The more clear a texture is before upload, the better it will look large. While someone "may" have divided a mesh plane into quadrants to increase the texture size, the ones I have seen were simply very good screenshots to start with. If you find one, you can right click  choose OBJECT  and INSPECT it and see how many and what size textures are used. 

 

For example this is a single 1024 texture on a prim. 

 

image.png.51801d9e11f7419773aad50b1519c2d9.png

 

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We would need to know what you saw to explain how they did it.

I suspect most residents use 1920x1080 screen resolution. A large 4-1024px-images image if displayed full screen would have the system discarding something like 75% of the image data. The extra resolution is only useful if you zoom in to point you only see a quarter of the image on your screen.

If you see large images in-world that are sharp and crisp, it may be skill and tech knowledge that allow them to present that nice image. In SL higher rez doesn't help as much as knowing image formats and sizing issues common to SL. If you present an image that is not uploaded using a non-lossy format and sized to work with SL's JPEG2000 storage format and also display it on a prim sized to get the image to a 1 to 1 pixel ratio... the server will jam the image into JPEG2000 format at the cost of quality then later the viewer will resize the image for display and lose a lot of the image quality. It is a PITA to learn how to do good images in SL.

Basically uploading a 1024x1024px PNG image with alpha channel is the best you can do. Then place it on a square prim, sides 1x1, 2x2, 3.5x3.5, or similar. After that it is up to the one looking at the prim, which you can't control.

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   Same thing also applies the other way around, so if you want to hang a picture on the wall that's .5 x .5 meters in size and use a 1024 x 1024 image, that image will be severely compressed when viewed at a distance.

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20 hours ago, Nalates Urriah said:

We would need to know what you saw to explain how they did it.

I suspect most residents use 1920x1080 screen resolution. A large 4-1024px-images image if displayed full screen would have the system discarding something like 75% of the image data. The extra resolution is only useful if you zoom in to point you only see a quarter of the image on your screen.

If you see large images in-world that are sharp and crisp, it may be skill and tech knowledge that allow them to present that nice image. In SL higher rez doesn't help as much as knowing image formats and sizing issues common to SL. If you present an image that is not uploaded using a non-lossy format and sized to work with SL's JPEG2000 storage format and also display it on a prim sized to get the image to a 1 to 1 pixel ratio... the server will jam the image into JPEG2000 format at the cost of quality then later the viewer will resize the image for display and lose a lot of the image quality. It is a PITA to learn how to do good images in SL.

Basically uploading a 1024x1024px PNG image with alpha channel is the best you can do. Then place it on a square prim, sides 1x1, 2x2, 3.5x3.5, or similar. After that it is up to the one looking at the prim, which you can't control.

Why "with alpha channel" in this application?

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7 hours ago, Ardy Lay said:

Why "with alpha channel" in this application?

PNG comes in two flavours of alpha, with and without alpha. The best you can hope to get into SL is the "with". But PNG without alpha works fine. The with alpha pushes the file to 32-bit, I think. So, "with" is the most complex image you can upload to SL.

For an added tweak to the image see: http://blog.nalates.net/2019/02/18/second-life-how-to-get-better-image-quality/

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I don't see how adding a forth 8-bit channel of data that I don't want to use in a photograph is going to help increase image resolution.  "Pushing it to 32 bits" as opposed to 24-bits is just wasting those additional 8 bits in the alpha channel.  Now, if you want the alpha channel for other reasons, that's fine.

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Not sure if OP was talking resolution of the image, or size of the object.  If the latter, search the MP for megaprim kits.  These contain copy-yes super-sized prims from before Linden changed the size limitations on new prims to 64 x 64 x 64 (meters).  Note that if you try to edit a megaprim, it will suddenly shift any of the objects dimensions that exceed 64 meters to now be 64 meters. 

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I'll try to find the locations where I originally saw the images. 

Is it possible that artwork, ie: graphic images that are vector based and can be enlarged, are added to a mesh and then have no limit in size? 

The images I saw were about 1.5 to 2 times taller than my Avatar. Maybe they aren't photography in the strictest meaning. 

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There are no vector image formats available or used within SL. All images are pixel images.

All images in SL are stored in JPG2000 format. See SL Image System in the wiki (last update 2007).

So, if you see it in SL it is from a JPG2000 source file downloaded from the SL assets system.

The conversion from acceptable formats at upload is also why in SL we don't have to worry about infected image files. (Reference)

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1 hour ago, Nalates Urriah said:

Have you worked with Media on a Prim? 

That question probably wasn't for me, but I will answer anyway.  I have used media on a prim for signs, an SVG clock face and an movie display with an SVG ATSC color bar pattern when there is no movie scheduled.  Very few people have media enabled so they don't see them.

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Posted (edited)

In none of these areas was anything special or unusual done with the images. Nor are any of these what I would consider large images. I consider them typical.

I think your question comes from misunderstanding what you are seeing on your screen.

Consider.

Your computer screen is likely 24” (0.61m) and that is measured diagonally from bottom left to top right. How can you see a 2x3 meter prim on that little screen? Because the computer is scaling the image.

The scaling is very fluid. Roll your mouse wheel. You can zoom out to the point a 2x3m prim is a single dot on your screen. Or zoom in until only a tiny tiny part of the prim fills the whole screen.

Now consider that prim having a 1024x1024px texture on a single face/side. When the prim is so small it is 1px across on the computer screen then the computer has to figure out how to place all 1024x1024 = 1,048,576 pixels in one pixel (dot) on your screen.

At the opposite end you zoom into the point where maybe only a 10th of the prim is visible to fill your whole computer screen. You can only see a 10th of the 1024x1024 image (102x102 = 10,404px). Those 10k of pixels have to fill your 24” screen that likely uses 1920x1080px = 2,073,600px. The computer is figuring out how to fake (2,073,600 - 10,404 😃 2,063,196 pixels.

The viewer and the computer cooperate to provide what it thinks is the best render of those 10k pixels on its 2mega pixel screen. Depending on what you are doing the image will render as blurry or pixelated and possibly a blend of both..

 

Edited by Nalates Urriah
Added video

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