Displacement from image issues

Started by ajcgi, March 23, 2011, 10:21:08 am

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D.A. Bentley

Exr-IO appears to have a 2GB file size limit.  :(

WAS

Didn't catch that. :( I wonder if it's a 32-bit limitation? A lot of plugins target 32bit Photoshp... for whatever reason.
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D.A. Bentley

No, I don't think it has anything to do with EXR being 32-Bit.  Different EXR readers/writers have different limitations.  For example, Teragen can output EXR's that are HUGE!  But other programs can't always deal with them.  Like Photoshop for example; it can load huge 4GB EXR files, but it can't save them with the standard (built-in) OpenEXR reader/writer.  There is Exr-IO, and also ProEXR, and others I imagine.  Programmers here on the forum might have more insight into why some formats have file size limitations.  Tiff also has a 4GB file size limit.  Recently I have been just using Photoshop PSB for everything I work on that is huge (It's 32-bit RGB and you can save files that are hundreds of GB).

D.A. Bentley

Quote from: WASasquatch on April 21, 2018, 02:08:14 am
Didn't catch that. :( I wonder if it's a 32-bit limitation? A lot of plugins target 32bit Photoshp... for whatever reason.


Actually I got a reply from the company that developed Exr-IO, and they said the 2GB limitation is a Photoshop limitation. 

bobbystahr

April 26, 2018, 09:06:43 pm #19 Last Edit: April 26, 2018, 09:11:54 pm by bobbystahr
Quote from: D.A. Bentley on April 26, 2018, 09:03:56 pm
Quote from: WASasquatch on April 21, 2018, 02:08:14 am
Didn't catch that. :( I wonder if it's a 32-bit limitation? A lot of plugins target 32bit Photoshp... for whatever reason.


Actually I got a reply from the company that developed Exr-IO, and they said the 2GB limitation is a Photoshop limitation. 


maybe try it in IrfanView...it's free and there may be a plugin.
Just checked and the is an EXR plugin, would that work. It's a 64 bit program, or 32; but if you run 64  use that one.

https://www.irfanview.com/64bit.htm
something borrowed,
something Blue.
Ring out the Old.
Bring in the New
Bobby Stahr, Paracosmologist

WAS

Quote from: Matt on April 14, 2018, 08:59:05 pm
Quote from: Oshyan on April 13, 2018, 08:52:09 pm
The Displacement of EXR (and any incoming file without georef/height information) is assumed to be 0-1, in meters.

- Oshyan


Actually it simply reads the pixel value in the EXR and that is the height in meters. The range you get will depend on what the exporting software writes into the image. Terragen's choices might be different from those of Gaea. I would encourage Dax to consider using the same mapping that Terragen does (pixel value = height in meters), because it eliminates the need to manually enter a scaling factor on a case by case basis.

Matt


32bit EXR files handle color depth and contrast differently than 16bit, probably where the changes are from. I'm not entirely sure why you'd need a 32bit EXR for Terragen, honestly. The effects where you'd assume artifacts may show up are pretty much useless to TG.
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Matt

Yes, 16-bit integer is different from 16-bit float. 16-bit integer (as in TER and 16-bit TIFF) is usually enough for most terrain needs, as long as the data is normalized to fill the space from black to white. But 16-bit float (as in 16-bit EXR) has variable precision which can cause visible stepping at high altitudes. I worked on a project last year where this was noticeable, so I needed to add support for 32-bit EXR to solve this. The alternative is to stay with 16-bit integer TIFF, and this will save some disk space, but the downside is that you have to keep track of where black and white are.

Matt
Just because milk is white doesn't mean that clouds are made of milk.

digitalguru

Quote16-bit float (as in 16-bit EXR) has variable precision which can cause visible stepping at high altitudes


Yes, I had the same thing before 32 bit exrs were introduced - see:
https://planetside.co.uk/forums/index.php/topic,21829.msg240240.html#msg240240     Reply #6

shows exactly that  :)

Quotebut the downside is that you have to keep track of where black and white are.


That's why I prefer 32 bit exr, the values are a real world correlation to Terragen.

I see a lot of post with people wrestling with large file sizes - for displacement I presume, and running into limits imposed by Photoshop and suchlike.

I have a solution that might work for some people - more info soon.