Another Orwarian guide (ramble) - working with 2D backdrops in SL

[Orwar]

   In light of a recent discussion elsewhere regarding backdrops, I thought I'd go through the building and lighting aspects of working with 'flat' backdrop images. Personally I prefer actually having a picture in-world when I take my picture, than doing a chromakey - though there are some benefits of using chromakey if you do have a high resolution backdrop that you want to use (but it also takes more work!). Alternatively you can always just cut out your subject manually .. But that's pretty labour intensive.

   Anyway. The only thing you'll need, is somewhere with rez rights to work. You could also wear the backdrop if you don't have anywhere with rez rights, but .. Plenty of sandboxes out there, so I'm not going to go into that here (and you'd need to rez the prim first somewhere anyway, so, meh).

   First things first, let's prepare our prim. All I've done here is press Ctrl + B to open the build menu, and rezzed a prim cube:

   You can rename it if you want to keep it in your inventory, though I always just make new ones whenever I need one, so I'm not too bothered.

   Now, I've stretched the cube into a 4 x 4 x 0.5 meter object, gone to the texture tab, opened the texture selector and just hit 'blank' in the texture picker. You don't have to make the texture blank, but I'm not a fan of the plywood texture and .. It saves me a minute amount of texture memory, so, yay? Next we'll need to find the texture we want to use. I found this public domain stock image of a beach that I'll use for this demonstration.

   Since the texture isn't in a 1:1 aspect ratio, I'll have a few options with how to map it - but I'm going to do the simplest thing and just resize the prim to match the aspect ratio. 1920 x 1280 = 1.5:1, so I'll just make the prim 6 x 4 meters for now. To use the picture, I'll download it to my computer.

   In the texture picker, select 'local', then hit 'add' and browse the file on your computer. I then select the face I want to use, and click on the texture in the picker to apply it. Note that it will only be visible on your end, for anyone else it'll be a plain grey, and local uploads are temporary, so if you relog it will disappear. Next, I just set up a pose ball and put myself in front of the backdrop.

   I had no idea what resolution to do the pic in as, well, it's just a demonstration pic - so I went with 16:9 and just blew it up to 1600 x 900, which is slightly stubbier than my native resolution. The current WL is just CalWL, and the exposure is a bit grim for a beach scene.

   Changing up the WL, you'll notice one of the drawbacks of using this type of backdrop - that shadow is way out of place, and just looks awful. I'll either have to adjust the sun position to make it go away, or I could make the backdrop fulbright to avoid any shadows being cast on it - but that too will look out of place as the colour scheme in the WL and the picture do not match:

   So, I can either turn the WL to a full black one (Phototools- no light) and use only local lighting sources, or I can find a decent WL with the right light style, and move the sun position to avoid the shadows, and then compliment it with local lighting (and turn off the full bright!).

   There, the lighting feels decent, although I will probably tinker with it a bit in editing before I'm done - but before I end the shoot, there's one last thing I want to do here ..

   Capture a depth map for the DOF. Now, you probably can use the in-world tools quite well, and you can certainly move the backdrop further or closer to help with that, but I've found that DOF tends to work poorly with alphas, such as hair, and it also doesn't scale well when you do use higher resolution images - so for the sake of control, I just do a depth map (you can find my thread about doing that elsewhere on the forums - I'm just too lazy to go find it right now!).

   That's all we need to do in-world, I didn't spend any L$ on uploads or buying any fancy bits and stuff, and it took me seconds (plus the time it took me to write here, of course). 

   So, with my depth mask and picture, I can bring it into Gimp and play around with it. 

   And the final shot. Much quicker and easier than doing a chromakey! It's not a technique I use very often as there are a lot of caveats to it, like lighting direction in the stock image and what lighting setup you use in-world (if the shadows of your subject are in the reverse, or even just off by a few degrees from the backdrop, it very quickly stands out), besides using 'RL pics' as your backdrop, your avi will look out of place - avatars do not look like real humans do, after all.

[Nalates Urriah]

Once you have the depth map edit it and increase the contrast... Go for black and white. Hair strands either get better or worse. Adjust to make the best selection of the hair.

Green screen can add reflected light causing color cast. Here is a tutorial on removing it:

 

[Orwar]

18 hours ago, Nalates Urriah said:

Hair strands either get better or worse. Adjust to make the best selection of the hair.

   The problem with hair strands and depth maps is that hair drawn on otherwise alpha'd 'chunks' of mesh will register as all being the same depth, at least in Firestorm. It's the same with DOF in FS. You can manually paint the depth mask in those areas, but that can be a fair bit of work.

   I think BDW tends to handle alphas and depths better, but I rarely use it.