HOWTO: Swap or Resize Wheels in PS/PSP

Discussion in 'HOWTO' started by Shude, Jan 11, 2004.

  1. Shude

    Shude MB Club Veteran

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    Following on from the first tutorial (HOWTO: car colour change in PS/PSP), in this second tutorial I am going to explain how to change the size or the style of the wheels on a car picture.

    Here is the car, it has factory 17" wheels on it.

    [​IMG]

    When looking for a picture of the wheels you want it is always better if you can find a picture of a car with the wheels mounted, then the relative shapes of the rim and spokes will be correct for camber, slightly turned front wheels or perspective. Here I will use an image of a Brabus w209 with staggered Styling VI multi-piece wheels (nice! :D )

    [​IMG]

    I think these would look nice at 18", so now it is time for some maths :) . 18" wheels are 6% larger in diameter than 17", so we need to measure the wheels on the original car and resize the donor wheels to make them look realistic. For ultimate realism I usually resize the original car so the tyres also match. The donor car seems to be at a slightly different angle to the car we are adding the wheels to, so it has been rotated 3 degrees anti-clockwise so it looks similar.

    The front wheel on the 6% larger version is 59x83 pixels. The donor front wheel is 131,180 pixels so the whole pic needs to be rescaled to match, this is 45%,46% of the size. When the picture has been rescaled you need to transfer the wheel texture to the larger version of the original car, you can do this with either the select method or the clone method.

    1. The select method.

    Just as with the car body in the previous tutorial, choose the lassoo "freehand" selection tool and click precisely around the wheel rim, the more points you use the more accurate the shape will be.

    [​IMG]

    When you have completely selected the rim, "Edit, Copy", switch to the larger version of the original car and "Edit, Paste, As New Selection". Move the wheel to the correct position on the car, when happy right-click somewhere else on the picture.

    [​IMG]

    2. The clone method.

    This method is similar to the previous tutorial, except that you need to be precise about which area to clone to which area. I usually right-click the clone brush on the very bottom or the top of the donor rim, in the middle, switch to the receiving car and click on the same point, this can require some judgement and practice. The beauty of using this method however is that you can use the rim of the existing wheel and just clone up to the very edge of it, so the outer rim is original to the picture and will look very realistic.

    [​IMG]

    Whichever way you chose to do it, you now have the wheel you want on a larger version of the car you wanted it on. The next step is to transfer this wheel onto the original car. The reason why there is an intermediate step between the donor car and the original car is that the tyre is also slightly different on a larger-wheeled car, in order to capture this difference we must now move some of the tyre to the original car as well.

    [​IMG]
     
  2. OP
    OP
    Shude

    Shude MB Club Veteran

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    1. The select method.

    Just like last time, you must select the shape using the freehand selection tool, but in this instance you must also select a section of the tyre outside the rim, there are usually markings or shiny reflections to work around.

    [​IMG]

    Once you have marked the shape out, "Edit, Copy", then open the original picture and "Edit, Paste, As New Selection". Move the selection to the desired position and right-click somewhere else to paste.

    [​IMG]

    2. The clone method.

    As with the last cloning process, you need to find a point on the picture that you can use in the original. This requires a good eye because no reference pixel exists, it is down to judgement. The centre of the wheel is an obvious place to start but this is not neccessarily where the centre of the centre-cap is, it is the direct centre of the elipse made by the rim of the wheel. Once you have found this imaginary point you can just clone the texture straight onto the original pic using as much tyre from the larger pic as you see fit.

    [​IMG]

    The front wheel is now done!

    [​IMG]

    The processes are the same for the rear wheel.

    [​IMG]

    See how the lower profile tyres highlight the arch clearance? Coming next: how to lower the car's ride height! :)
     
  3. Brian WH

    Brian WH MB Club Veteran

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    Last edited by a moderator: Feb 19, 2004

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