If you'd like to follow this Tutorial using your own LightWave software, you can download the body mesh here:
OK, the idea is to create a square outline on either side of the body just below the cockpit, each of which will receive an image. We'll use a couple of different images to illustrate some important points.
Here's the setup just before clicking the 'Create' button. Notice that the new Surface to be created by the Stencil process has been called 'Decal', but you can type in any suitable name.
If you don't want a symetrical arrangement of decals on both sides of the body, reduce the 'penetration' of the Drill through the Target mesh. It will only stencil onto the Polygons it touches.
The stencilled areas 'inherit' the Surface attributes of the Drill.
Here's what the Preview looks like, complete with those fuzzy intake polygons.
The first is an image bearing the logo of Lidl, the supermarket chain. No, I don't have shares in Lidl, they just have a nice square logo! The second one is a square image bearing the number '24' in black with a white outline and dark green background. The dark green was originally intended to match that of the Lotus paintwork, so the background blended in with the bodywork. Again, this is the amateur's method that doesn't work very well. I'll show you the proper way!
Now applying the Lidl image is pretty easy. It's got its own colour scheme over the entire area and a white outline, so it will sit nicely within the 'Decal' outline. We won't have to worry about matching up anything with the surface of the body mesh.
The '24' sticker is different. It's got the square shape OK, but we don't want to see that in the render. We only want to see the number '24' and nothing else. The 'background' in this image should have the same attributes as the body mesh. Problem is, you can't control the surface attributes of an Image that well. OK, you could make the background colour the same and you may get away with it. But what if the body attributes have to be morphed or animated....? Read on.
In Layout, load the Lidl image into memory using the Images menu.
Now, click the Surfaces button and on the pop up Surfaces Panel, select the body surface. It's called 'Body' in the download which accompanies this Tutorial. Give it a suitable colour and any other attributes you fancy. The lighting should come from somewhere above and to one side of the Camera. Keyframe (0)/All Items to fix everything in place.
Go back to the Surfaces Panel and select 'Decal'. This is the square area onto which the Lidl image will be projected. Leave its colour at default. It won't be seen anyway, because the image will cover it up. Click on the 'T' button alongside the colour selector. This will pop up the Color Texture panel for the 'Decal' surface. Here, you control how the Image will be projected (mapped) onto the 'Decal' surface.
Under Texture Type, select 'Planar Image Map', since we want the Lidl image to be applied as a flat map.
Under Texture Image, select the Lidl image you loaded earlier.
Next, select 'X Axis' as the Texture Axis. This will project the Lidl image onto the body from the 'Left' as described earlier.
Now click 'Automatic Sizing'. A warning will pop up telling you that any existing settings will be replaced. OK this and get back to the panel. By setting up Automatic Sizing, LightWave will adjust the dimensions of the image to fit exactly onto the 'Decal' surface. If you didn't set up Auto Sizing and the original image was larger than the surface, only part of it would be applied. If the original image were to be smaller than the surface, LightWave would tile the image, providing the 'Height Repeat and 'Width repeat' buttons were active. So, always select Automatic Sizing when applying decals.
You can see the dimensions that LightWave has assigned to the image by clicking on the 'Texture Size' button. This pops up a small panel showing the X,Y, Z dimensions (in the system's Unit of measure). In the case of a planar image, one of the dimensions (Y in this instance) is redundant and may show 1.0 or another size. It's redundant because this particular projection is horizontal. With vertical projections, the Y axis becomes paramount. All image dimensions, redundant or not, must be greater than Zero.
OK, click on 'Use Texture' to close the Texture panel and get back to the Surfaces Panel. Ensure that the 'Smoothing' button is active, it gives a better result. Now click 'Continue' to get back to the Layout screen and run a quick render to see how things are going. It should produce something like this....
Great! If you're intending to produce a single picture of the left side of the car, the job's done. But what about the other side? Remember the stencil was applied completely though the body mesh, giving us an identical 'Decal' outline on the right side too. Let's take a look.
Go back into Layout and rotate the body so its right side faces the Camera. What have we got?
Jeepers! The image is reversed!
Now you may be thinking that all this hassle is no better than having to paint two different sides, a top, a front and a back view image of the body with the decals the right way round and doing it the old way! You're wrong! This is better, believe me! And the solution to Dr Watson's dilemma is but a few mouse clicks and a minus sign! OK, plus a little more logic!
The reason the right side is wrong is 'cos it shares the same Surface name as the left side...'Decal'. LightWave treats all Surfaces with the same name as the same thing. But our two decal squares must be treated as different if they are to get their projected image correctly orientated. So how do we do that? Here's how...
Import the body mesh back into Modeler.
Use the Polygon/Stats tool to select all the areas called 'Decal'.
In the Top view, home in on these areas using the zoom In button.
Using the Polygon/Surface menu, rename all these surfaces 'DecalLeft'.
Use the Lasso selection method (RMB) to deselect the decal which is actually on the left side of the body (as seen by the driver). What remains highlighted is the decal on the right side.
Rename this area 'DecalRight'.
Save the revised body mesh under a suitable name.
Export the mesh back into Layout.
For the 'DecalRight' surface, the projected image has to be 'reversed' as it's projected. Now it's coming in from the +X direction and that's fixed. So, we can only modify the Y or Z component of the projection. As noted earlier, the Y component is redundant because the projection is horizontal. So, the only the Z component is available and that's what will do the trick.
Go into the Texture Size panel and type in a minus sign in front of the Z dimension. Be sure to make it stick by pressing the Return key. Exit the Size panel.
Exit the Surfaces Panel and run a render of the right side of the body. It should look like this...
Now that's a relief, but once you get the trick into your head, it's all so easy-peesy!
Anyway, let's repeat the surfacing routine we used for Lidl with this new sticker. It's pretty obvious we'll get this....
Now I just don't feel like loading the '24' decal back into a paint package and repainting the background red. In fact doing so could turn out to be a real pain in the butt. Why? because the image is antialiased and changing the background colour is not the only problem. It's all those hundreds of tweeny pixels that need tweeking as well. Forget it! We need the Alpha Channel for this one!
Now I know you're well ahead of me already, but slow down. We'll have to get out Photogenics anyway, 'cos we now need an Alpha version of the '24' image. Even DPaint4 or 5 will probably do, but you'll have to check (I've forgotten so much!). The basic idea is to make all the bits of the image we do want to see white and all the bits we don't want to see black. I reckon the easiest way to do this (antialiasing remember) is to change the image's palette to just the two colours, black and white. Everything else, size and shape, should remain as in the parent image.
However you do it, the Alpha image should look something like this.....
I've placed the original close by, so you can see how everything corresponds. Remember, the Alpha image is a filter and we'll see right through the black areas but not the white. In the black areas, we'll see the attributes of the surface underneath the image.
Now remember to Save this new image with a suitable name like '24alpha.jpg'.
Good, we're getting into the home straight! But there's another important thing to remember right here.
So, before you start rendering with the Alpha Channel active, make sure the surface that will receive the image projection is given the same attributes as the rest of the body mesh. In the current case, make 'em red.
Go into the Surfaces/Color Texture panel for the DecalLeft surface and select the '24' image as the Planar/Texture Image and select the '24alpha' image as the Planar/Texture Alpha Image.
Set the Image Axis to X as before and don't forget to Auto Size.
If you wish to render the DecalRight area, repeat all this for the other surface, but remember to reverse the projeced image by making the Z size negative.
The rendered body should now look like this....
And the other side like this....
Here's one of the 'WaveGuide' banners that we decided to stick on the top surface of the body, either side of the cockpit. This one is for the 'left' pod.
Again, only the red/yellow parts of the image were required. This decal was given a black background, but it could be any colour because the Alpha version will filter it out.
Here's the Alpha image to do the trick.
Now you could use a large rectangular Drill shape to stamp the outline if this image onto the body mesh. However, that's a pretty cumbersome size and it may impinge on other areas of the mesh that have attributes different from the image's intended background. The neatest thing to do is make a specially shaped drill to create a nicely shaped outline for the graphic. Here's how.
The Modeler screen should now look something like this....
You'll remember that the Drill used to stencil the outline of the decal must be an enclosed solid, so the next step is to extrude the polygon along the Y axis to make a sort of kinky box. This gives us the required Drill as shown here....
OK, all we need to do now is repeat the stencilling routine into the top of the body mesh.
Remember that the projection axis in this case will be Y.
Remember to give the stencilled surface a suitable name (eg: waveguidedecalLHS) but give it the same surface attributes as the bodywork.
A separate image is required for the right hand side, because this isn't a case of through projection. You will have to save it upside down so the Top view is correctly orientated.
Here's how the decal looks when rendered onto the bodywork.
How you go about stencilling the outline for the decal really depends on what the viewing angle for the render will be. Remember, you can't alter the projection axes, those are fixed. So, what you can do is alter the shape of the canvas according to your desired viewpoint.
Any decal applied to an inclined or curved surface can only be seen without distortion from one specific viewpoint (along the projection axis). From any other viewpoint, the image will be stretched in one dimension or another. It's a bit like road markings. From your car they look OK, but to a pedestrian on the roadside they are all stretched out.
So, let's say you want to place a circular decal onto a surface inclined at 45 degrees. Clearly, a circular decal is only circular when viewed at right angles to the surface. From any other angle, it will appear elliptical. People designing images for inclined or curved surfaces know about this phenomenon and compensate for any foreshortening by distorting the image. And you can too.
To keep things simple, in Modeler I created a flat target surface of triangular polygons and set it up at 45 degrees to the horizontal. Here's the picture....
Now I'd like the circular decal to appear truly circular when viewed at right angles to the surface. Here's the image, together with the appropriate Alpha version.
So, the first thing to do is create a Drill. Since we'll be using the Alpha Channel, the drill can be any shape, providing the circular image will fit inside its cross-section. Another square-sectioned box will do. Just make the square the same size as the decal's intended diameter. Remember LightWave will stretch the image to fit the stencil. Here's the Drill being adjusted to the target.
The next step is to repeat the now familiar 'S Drill/Stencil' operation. This will stencil a distorted square when viewed from the projection axis, but a true square as seen from the Drill's axis. Here's the setup...
OK, let's render the inclined Surface using the Lotus image and its Alpha version. They were projected horizontally on the Z axis. The first is the view from the projection axis. The second is the view at right angles to the target surface.
You follow exactly the same procedures for image projections in the Y and Z axes. These will place decals respectively on the Top/Bottom and Front/Back of LightWave objects.
Remember to use the logical minus switch in the Size panel when you've stencilled into the 'negative face' of an object. That's a face which looks towards the negative side of a projection axis.
Oh yes, a final comment. Having thought about it a bit more, I guess you could use this method for putting some tattoos onto a nice curvy body! But for that, you'd better write your own Tutorial! Thanks for sticking with it.
Here's a few more renders from the Lotus project. All the decals were created using the methods described here.
If you find any obvious errors in this Tutorial please email me and I'll fix them at once.
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