"danyolgiax" <d.o### [at] gmailcom> wrote in message 
news:web.44586fbe319c0b1aa8eb78fb0@news.povray.org...
>
> note that train.png is 300x100 png image!
>
> Ok it works! but I can't understand those values:
>
> translate <1.5,0.5,0>
> scale <3,0,0>
> translate <-4.5,-0.5,0>
>

Hi Dany,

The two translates seem to cancel each other out and the scale factor should 
be <3,1,1>.You should find a warning in the message stream to tell you that 
scaling by zero is not valid and that POV-Ray has automatically substituted 
'1's where you specified '0's

Despite the resolution of the image, it will always get mapped initially to 
a 1 unit square with it's bottom left corner at the origin and  its top 
right corner at x=1,y=1. By scaling the image up by a factor of 3 in the 'x' 
dimension you effectively restore the original proportions of the image.

Scaling takes place relative to the origin, so when you use translate 
'<1.5,0.5,0>' you move the bottom left corner to x=1.5,y=0.5, then scaling 
by x*3,y*1 puts the bottom left corner at x=4.5,y=0.5. Your second translate 
therefore moves the bottom left corner back to the origin.

So, all in all these three lines do the same as just specifying:
scale <3,1,1>

Hope this helps,

Regards,
Chris B.

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