Raytracing: why are the spheres in the image below appear stretched?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











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Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image there are 2 ellipsoids side by side. I just can't fathom why it is so, no matter how many time I looked at the code. Can anyone explain to me? Here's the link to the source code.
https://github.com/petershirley/raytracinginoneweekend






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    This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
    – PaulHK
    3 hours ago














up vote
1
down vote

favorite












enter image description hereenter image description here



Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image there are 2 ellipsoids side by side. I just can't fathom why it is so, no matter how many time I looked at the code. Can anyone explain to me? Here's the link to the source code.
https://github.com/petershirley/raytracinginoneweekend






raytracing







share|improve this question

















  • 1




    This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
    – PaulHK
    3 hours ago












up vote
1
down vote

favorite









up vote
1
down vote

favorite











enter image description hereenter image description here



Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image there are 2 ellipsoids side by side. I just can't fathom why it is so, no matter how many time I looked at the code. Can anyone explain to me? Here's the link to the source code.
https://github.com/petershirley/raytracinginoneweekend






raytracing







share|improve this question













enter image description hereenter image description here



Some context. Above are the code and the resulting image for it in Peter Shirley's Raytracing in one weekend's book. As you can see from the code, he adds in some spheres. And yet in the final image there are 2 ellipsoids side by side. I just can't fathom why it is so, no matter how many time I looked at the code. Can anyone explain to me? Here's the link to the source code.
https://github.com/petershirley/raytracinginoneweekend






raytracing




raytracing






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asked 3 hours ago









Manh Nguyen

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305







  • 1




    This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
    – PaulHK
    3 hours ago












  • 1




    This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
    – PaulHK
    3 hours ago







1




1




This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
– PaulHK
3 hours ago




This looks normal and is caused by the perspective camera being close to the spheres and having a large FOV value.
– PaulHK
3 hours ago










1 Answer
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Shapes appearing stretched in the periphery is a consequence of perspective projection. The wider the field of view (FOV) is, the stronger the stretching effect gets.



To demonstrate the effect I wrote a quick example on ShaderToy: https://www.shadertoy.com/view/MltBW2



As you can see on the images below (corresponding to FOV of 40, 80 and 120; if I didn't make any mistake), this becomes especially noticeable with wide FOV, like 90° and above.



FOV 40°FOV 80°FOV 120°






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    Shapes appearing stretched in the periphery is a consequence of perspective projection. The wider the field of view (FOV) is, the stronger the stretching effect gets.



    To demonstrate the effect I wrote a quick example on ShaderToy: https://www.shadertoy.com/view/MltBW2



    As you can see on the images below (corresponding to FOV of 40, 80 and 120; if I didn't make any mistake), this becomes especially noticeable with wide FOV, like 90° and above.



    FOV 40°FOV 80°FOV 120°






    share|improve this answer


























      up vote
      4
      down vote













      Shapes appearing stretched in the periphery is a consequence of perspective projection. The wider the field of view (FOV) is, the stronger the stretching effect gets.



      To demonstrate the effect I wrote a quick example on ShaderToy: https://www.shadertoy.com/view/MltBW2



      As you can see on the images below (corresponding to FOV of 40, 80 and 120; if I didn't make any mistake), this becomes especially noticeable with wide FOV, like 90° and above.



      FOV 40°FOV 80°FOV 120°






      share|improve this answer
























        up vote
        4
        down vote










        up vote
        4
        down vote









        Shapes appearing stretched in the periphery is a consequence of perspective projection. The wider the field of view (FOV) is, the stronger the stretching effect gets.



        To demonstrate the effect I wrote a quick example on ShaderToy: https://www.shadertoy.com/view/MltBW2



        As you can see on the images below (corresponding to FOV of 40, 80 and 120; if I didn't make any mistake), this becomes especially noticeable with wide FOV, like 90° and above.



        FOV 40°FOV 80°FOV 120°






        share|improve this answer














        Shapes appearing stretched in the periphery is a consequence of perspective projection. The wider the field of view (FOV) is, the stronger the stretching effect gets.



        To demonstrate the effect I wrote a quick example on ShaderToy: https://www.shadertoy.com/view/MltBW2



        As you can see on the images below (corresponding to FOV of 40, 80 and 120; if I didn't make any mistake), this becomes especially noticeable with wide FOV, like 90° and above.



        FOV 40°FOV 80°FOV 120°







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited 1 hour ago

























        answered 1 hour ago









        Julien Guertault

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