#missing alpha channel
23 messages in this thread
Thanks for your response. But questions still remain.
1) Regarding the alpha channel problem: The attributes of the image
used for bumping and texture were identical. That's where I was baffled.
They were both set for decal. I tried "ignore" but got the same warning.
I also tried different but matching values. No good. I decided to kill
the texture map and give up.
2) Regarding the missing alpha channel: Good advice but useless. As I
mentioned, the alpha channel is missing according to PhotOshop, QFX,
and examining the file in hex. I asked 2 other video production facilities
about this problems and they also have a problem with missing alpha
information. They gave up as I have. But I'd like to know what the story
is before I write it up in the newsletter. With alpha on and set to
no-split, where's the alpha information? Try it yourself. Render an image
and look at the alpha channel in QFX. Let me know what you get.
Good Luck.
– Gregory MacNicol
Gregory,
I should probably wait for Gary's response, however, regarding your
second problem, I've done several 32 bit renderings in the past few weeks with
the main purpose of going into Photoshop and using the alpha as a mask, and I
have not had a problem. Out of curiosity, have you tried doing a composite in
video post with a 32 bit TGA rendered against black going on top of a bitmap
background. I'm wondering how 3DS will read the file.
David
Comments:
1) Re alpha channel 2x use msg: If you can come up with a .prj file that
illustrates the problem, archive it up with the maps and send it up to me and
I'll tell you exactly what's going on with it.
2) Re the "missing" alpha channel. I absolutely guarantee you that 3DS
creates perfect alpha channels. If you're having problems finding it, I can
get you in direct contact with plenty of other folks who use Hires QFX,
Photoshop, or any other 32-bit paint program. If you'd like to send me a .prj
file that you're having problem getting an alpha channel from, feel free to zip
it up and send it to me via email and I'll tell you exactly what to do about
it.
– G
PMJI, but I want to echo Gary's remarks — 3DS does product Alpha; not
only do I use the Alpha files in Photoshop with no problems, but I
use the 3DS with alpha with my Video Machine (which composites the
alpha perfectly as transparency information to be mixed with live
video). All I do is produce the alpha TGA with no alpha split on.
I've had the same question, with a simple semi-xparent object the
rendered file is still only 24 bit in photshop or alchemy. Even on
the Vista card there is no image data on the alpha line. It does
however work with a file that was provide from an SGI ?
Darren,
<< I've had the same question, with a simple semi-xparent object the rendered
file is still only 24 bit in photshop or alchemy.>>
Render-Setup-Options-Render_alpha=Yes
TGA_Depth=24
Alpha_Split=No
…should give you a 32 bit file and not a 24 bit file. (see
page 7-210 Render-Alpha 1st sentence.)
jonas[adesk]
You're not rendering with any kind of background are you? — an object against
the black default background, so that it will generate the right alpha is the
way to go.
If you have the settings correct (as Adesk recommends) and render against a
black background I don't see how you can't get alpha info. PS should correctly
show that file as having alpha when you bring it in (it always has for me).
Gregory,
Here is my checklist for alpha output:
1) File COMPRESSION: OFF! <== Sneaky Item (got me)
2) Background: NONE
3) 24 bpp
4) alpha ON, split OFF
The fact that 3DS does not write compressed 32bpp TGA files is a bit of a shame
– maybe Truevision never documented such a format?
(excuse me if I have botched my reply on this thread. I am using the
AutoSig navigator and have had trouble getting message reply to
work)
Ron Grant – Delta Graphics
Ron:
>> The fact that 3DS does not write compressed 32bpp TGA files is a bit of a
>> shame…
Are you sure? I seem to recall doing this, or am I mistaken? What program are
you taking the file into? Could that be it?
Greg Pyros
>>alpha output…
I may have missed something here, but are you saying you can't get 3DS
to produce a compressed TGA file with alpha channel data? Something
is confused here – I thought I did that all the time. I just ran a
test rendering, TGA, 512*486, 24 bpp, no background, alpha as noted:
COMPRESSED, NO ALPHA, File Size=248294
COMPRESSED, ALPHA ON, File Size=319584
UNCOMPRESSED, ALPHA ON, File Size=995867
Both files rendered with ALPHA ON display alpha channel in the
materials editor and load correctly with alpha into Altamira
Composer. Which version of 3DS are you using?
John, Greg P. and "all readers" Sorry! I botched my claim about "no
alpha in compressed files". The real catch (at least in 3DS R2.0)
appears to be: With UseAlpha=YES,TGADepth=24,AlphaSpit=OFF:
Rendering to Display then saving to disk using SaveLast image results
in a save of a 32 bpp file, but one with a solid opaque alpha channel
(all 255's). Rendering to Display & Disk generates the same file
size, but with a valid alpha channel. (I made sure Background was
NONE and Atmosphere NONE) for the above. My display software is a
custom animation player for Targa series frame buffers that I will be
posting a "probe for interest" in the next day. Thanks for checking
out my bogus claim. This forum is wicked. Ron Grant – Delta Graphics
>> Thanks for checking out my bogus claim. This forum is wicked.
That may be the first time it has been called that, but we take it in
stride! Did you write the custom animation player? Sounds like fun!
>> AlphaSpit=OFF:
I'd keep it off, also. Makes for a messy mousepad! <g>
Greg, >> Did you write the animation player?…
Yes, I am a graphics hack from back to Apple II days (1980). I bought
3DS2 and a Targa+ 64 1.5 years ago and have spent a good chunk of
time learning 3DS and writing software for Targa board from the
ground up.
To make my recorder/player ready for the masses I have to go back and
add flexible hardware configuration, i.e. IO&Memory map addresses are
hardcoded + need to write some documentation…
Now that I have corrupted this "missing alpha.." thread I will try to
get the description for my player up.
Greg,
>> Alpha Spit=OFF … it makes for a messy mousepad!
I couldn't for the life of me figure out what you meant.
Then I read the reply again – Oh Sit! I get it. Ron.
I'll bet Ron is from New England, maybe Maine. Wicked is a very old
term meaning "great". My grandmother used to use it!! I think I'll go
drink a frappe now.<g>
Ted:
Hello again!
>> New England…
Ah, so AlphaSpit is a term from your area! That explains it! <g>
Greg Pyros
Are you gonna have a Grinder with that, Ted?<g>
-Alan
>> I think I'll go drink a frappe now.<g>
How do you do that up there? Would you get a glass from the cupboard
(cabinet), put it on the sideboard (counter-top) and add milk from
the ice-box (refrigerator)? Or do you run out to the dooryard
(driveway) and hop in the car and get one downtown (1/2 hour away)?
Can you even get there from here? <wicked big grin>. If you order a
milkshake will they still forget the ice cream? Is it obvious I
married someone from a family from up north? BTW — Post production
is done on our project. I'll get you a copy.
David, RE: "wicked" Sorry, I am from Dallas. Y'all take care.
Good one Dave, I'll call you on Monday.
TedB
>> Good one…
Ayuh, but only a New Enlander would find the humor in it. <g>
You are correct, in 3DSr2, the save-last-image function does NOT save
the alpha channel. It saves it in r3, however!
RE: save-last-image now saves alpha in Release 3
Great! I purchased the upgrade a couple of weeks ago and really
should have tested it along with Rel 2. Just got a little lazy.
3DS Rel 3 is totally wicked. It really makes we want to meet with
other upgrade users in Dallas, read the new features list aloud, so
we could all hear a room full of oohs and ahs.