This coloring of reflection is rare even among conductors, but it does occur in some everyday materials e. Insulators as a general rule do not exhibit this effect, and their reflections are uncolored. Finally, electrical conductors will usually absorb rather than scatter any light that penetrates the surface. This means that in theory conductors will not show any evidence of diffuse light.
In practice however there are often oxides or other residues on the surface of a metal that will scatter some small amounts of light. This is sometimes preferred as a simpler means of creating materials, but is not necessarily a characteristic of physically-based rendering.
Augustin-Jean Fresnel seems to be one of those old dead white guys we are unlikely to forget, mainly because his name is plastered on a range of phenomena that he was the first to accurately describe. It would be hard to have a discussion on the reflection of light without his name coming up. In computer graphics the word Fresnel refers to differing reflectivity that occurs at different angles.
Specifically, light that lands on a surface at a grazing angle will be much more likely to reflect than that which hits a surface dead-on. This means that objects rendered with a proper Fresnel effect will appear to have brighter reflections near the edges. Most of us have been familiar with this for a while now, and its presence in computer graphics is not new. Yes, really — any substance can act as a perfect mirror if it is smooth and viewed at the right angle!
This can be counterintuitive, but the physics are clear. The second observation about Fresnel properties is that the curve or gradient between the angles does not vary much from material to material. Metals are the most divergent, but they too can be accounted for analytically. What this means for us is that, assuming realism is desired, artist control over Fresnel behavior should generally be reduced, rather than expanded.
Or at the very least, we now know where to set our default values! This is good news of a sort, because it can simplify content generation. The shading system can now handle the Fresnel effect almost entirely on its own; it has only to consult some of the other pre-existing material properties, such as gloss and selectivity.
Qukk stop here. Thank you. Since when does the format determine the actual output? It does not matter if you use png or tga, both formats are losless. The only difference may be in size. If you really think something like this, you have no clue how textures work.
PNG by default because its easy, by alpha support from photoshop is non-existent for. PSD has some nice added benefits. Should the memory size of a texture matter?? No matter if its bmp or jpg. Well what do you use for your normal maps? That is why it is called a Bit-map every single bit is mapped out along with every color the only thing you can do to make a bitmap smaller is to palletise it down to 24,16,8,4, or 2 bit. You really should learn about this stuff before you go and tell new people maxims that are completely untrue.
I recommend Wikipedia, or just reading in general, guessing will make you look silly. I was asking myself what was the best format between bmp and jpeg for game blender?
TGA is native to blender and requires no additional DLL files to run but can be big PNG is the best overall, you can compress them if you want, they can have an alpha channel too. We really need DXT. I use JPG for nearly everything.
Bitmaps are a really bad idea and I never use them at all. GIFs are not limited to colors. Please take a moment to consider if this thread is worth bumping. Recommended Posts iamyourneighbour Posted January 2, Share Posted January 2, edited Hi all, I have always used JPEG for SL developments since the size is smaller and in a literal sense would reduce download time, but how about performance considerations?
As I understand it all uploads get turned into jpgs jpeg I think but I have no idea exactly what that is. Do some tests on your own and decide. They support an alpha channel, which JPG does not. Almost as important, they support layers, so you can build up an image from a composite of sub-images with different opacities, luminosities, etc.
JPG gives you none of that. I never use JPG. Its only advantage is file size. Never store something with sharp edges, like a sign or a picture of text, in JPEG format. It will look terrible. I know there already are three good answers but to make it absolutely clear, Second Life only supports one image format, JPEG Apart from the JPEG limitations Rolig and Animats mentioned, it should not matter which file format you choose to use locally.
I say should because there may be some minor differences in how efficiently the uploader handles the conversion from different formats. What viewer you use to upload may actually matter since they use different JPEG libraries to convert the images. Firestorm uses Kakadu, a rather expensive commercial library. Kakadu used to be regarded as the best option but things have changed and the official viewer switched from Kakadu to OpenJPEG recently.
It may only be a matter of time before Firestorm does too. The format soon turned out to be a bit too limiting so it didn't take them long before they started from scratch and in they launched the everything-but-the-kitchen-sink JPEG It's not the most efficient format for lossless compression typically it achieves compression rate that way while PNG tend to achieve 2.
PNG also seems to have a better pixel loading sequence with less annoying not-yet-fully-loaded images. I suppose the explanation is that JPEG is the only format that offers a choice between lossless and lossy compression and although we don't really use the latter in SL anymore, it's too late to change.
For me, I never detected a difference, and in gimp, I've found it much easier to use tga for export. So seeing that conversion to JPG is always a bit of a letdown. I can see a discernible difference in resolution and quality of an upload depending on the viewer I use.
In my opinion, Firestorm is hands down the best in terms of upload quality. I hope it doesn't change! What happens if you try to upload a texture that's already in jpg format? Does it still get decrompressed and compressed? Yes, that's the whole point. The JPEG files are created as progressive files - reading the first part gets you a low-rez image, reading more gets you a higher res image, and reading it all get the full image.
The viewer's texture system uses this feature heavily. The difference is only in the file suffix. Both formats provide low resolution "early" versions of the image but the way they are generated are very different.
JPEG uses frequency decomposition, essentially it starts with a version with a heavily lossy compression, then progresses through increasingly less lossy images. PNG has interlacing, using the Adam7 algorithm. That's a much simpler process, only based on the order the pixel are sorted and delivered and it also seems to provide a sharper and more satisfying early image.
The image simplification method added to VR headsets recently to speed them up with a minimum of quality loss, is essentially the last stage of Adam7 reversed. PNG is lossless and compresses images quite well, but the way it handles alpha limits its use.
0コメント