Particle texture basics

jma
jma Website User Posts: 84
Can anyone link me to something that explains particle textures on a really basic level- like what is an alpha channel, how do I create one, etc?
Everything I read online assumes you already know this, but everyone's gotta start somewhere (or is it just me?)

Comments

  • Nate066
    Nate066 Website User Posts: 191
    edited April 2013
    An alpha channel is the transparent part of the image. You have to save the image as a .png to retain it's alpha channel. As for learning this stuff just play around with the settings and tools. You will eventually learn what it is and how to use it. Also search Wikipedia
  • jma
    jma Website User Posts: 84
    What about with things like the 'detonation films' footage. Can you change a colour into an alpha channel (or is that pretty much what the keying does)
  • Nate066
    Nate066 Website User Posts: 191
    If its pre-keyed then you can just import it and use it. But if its not pre-keyed as its still on the background or greenscreen then you will need to key it. Pre-keyed footage has already keyed it for you. If its shot on a black background use Luma Key as it will remove the black areas. The hard part is getting it so it doesn't look fake. I find the best way to do this is to feather the luma key then color grade it. To feather it since the luma key doesnt have this option add a matte cleaner under the luma key (Order of effects and layers is very important) then just feather it using the feather option. Color grading a shot can very but the way i commonly do it is to start with color correction, contrast, sharpen, to get the look i want the i use the other tools in the color grading panel to get the feel of my shot. I also use the Letterbox effect as it give a more cinimatic feel. If you need more help the hitfilm community is awesome way to go but also check out FilmRiot as they have tons of stuff that you will find interesting. FilmRiot now has there own channel but before they had there own they used revisions3 youtube channel so the videos are split up between them. All new film riot videos will be posted on the film riot chanel
    Revision3 FilmRiot(You will have to look through the videos since they never made a playlist of them): http://www.youtube.com/user/revision3/featured
    FilmRiot Main Channel: http://www.youtube.com/user/filmriot
  • jma
    jma Website User Posts: 84
    That was so amazingly useful. Thank you for your thoughtful and informative post!
  • AxelWilkinson
    AxelWilkinson Staff Administrator, Imerge Beta Tester, HitFilm Beta Tester Posts: 5,247 Staff
    edited April 2013
    An alpha channel is basically a mask embedded within an image.  It specifies which portions of the image should be transparent and which should be opaque.  It displays as a greyscale image, where white is opaque, black is transparent, and grey is semitransparent.  The darker the grey is, the more transparent it is.
    So, to create your own textures, you need to create images with transparency to define the shape and opacity of the texture.  There are two ways to go about this, basically.  One is to start with an image, and create an alpha channel to hide parts of it.  The second, is to start with an empty, transparent canvas, and only paint in the areas you want.  The specifics of how these work will depend on the image editor you are using.  I mainly use Photoshop, which is great for this, but is also pretty expensive, so I realize not everyone has access to it.  There are lots of more affordable options out there, including GIMP, which is free), but I'm not familiar enough with their interfaces and layouts to give detailed instructions.
    Its also very important what image format you use to save the textures, since not all image formats can store an alpha channel.  JPEG images, for example, cannot contain transparent areas.  PNG is generally the best format to use for creating textures.
  • jma
    jma Website User Posts: 84
    Extremely useful. I think I have learnt more things since starting with hitfilm than I did doing a BA in film. Every time I learn something new it just exposes how much there is to know!
    It's been the same with teaching; a student wants to know something or comes up with a problem, so both me and the student end up learning something new. Every time a group of kids comes through who think I know everything I have to have a laugh, as sometimes I feel spectacularly ignorant.
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