I’ve been using Autocad14 to produce architectural models and have recently started to try and use Blender for the final renderings.
One feature in Acad14 I allows me to place alpha images along the scene and these are always facing the camera; i don’t need to rotate these every time I need another viewing angle.
My questions are:
How can i use alpha images (of people or trees) in Blender?
Can these automatically face to the viewing plane?
thanks for any answers
nuno gouveia
Alpha images could be applied to a plane as an image texture, then you could have the planes track the camera using a track to constraint. It might require some tweaking, but it should work.
Dreamsgate: no tweaking required; that’s it exactly. In the Map To, select color and alpha.
Could you explain better your idea? I’m a newbee at blender…
thanks
yeah, they were bad answers 
firstly, the texture. Load it up in the texture buttons, then in the material buttons turn the alpha down to 0. (The alpha slider is the one underneath the r, g, b sliders) Then in the map to tab press ‘col’ and ‘alpha’ to have the texture affect the colour value and the alpha value of the material.
Next the tracking. Select the plane (or whatever it is you use for the texture), then the camera. press Ctrl+T and choose ‘track to constraint’. Now the plane will track the camera wherever it goes.
One last thing, in case the plane (or whatever) isn’t tracking the camera as you’d like it to, you can select the plane and go into the object buttons (F7), then under the constraints tab you can choose what axis you want to be facing the camera (x,y,z,-x,-y,-z etc). for further ease of use you can turn on the axis display for the plane in the draw tab. Just hit ‘axis’
Anyway, hope that was of some use.
Add a plane Give it a material. Set “Z Transp” button. Turn alpha slider down to zero. On the “Map To” tab click on “Alpha”. Make sure that youm only click once, if it turns yellow it will give you a negative alpha.Go to texture buttons (F6). Click “Add New”. Click on the word “None” and select image. Click “Load Image” and find the image that you want to use. Click on “Use Alpha”. Go to physics buttons (F7) Click on “Add Constraint” button and select “Track To”. Type in the word “Camera” in the “Target” field. Now in the “To:” field click “Z”, and in the “Up:” field click “Y”. Now your image plane will always face the camera. There is a way to force the plane to cast a shadow based on the alpha channel in the image rather than the jack-ass square shadow that the plane is going to cast but I’ve never been able to get it to do this so someone else will have to help you with that. If you initially see black where your alpha transparency should be then enable “Ray Transp” and then re-enable “Z Transp”. I don’t know why, but every computer that I’ve ever used Blender on requires this step
D’oh! You beat me to the punch M@dcow.
ah…hahaha…yeah, forgot the ‘ztransp’ part, well done Rambobaby.
thanks guys, i’ll try that.