<p style="font-family: arial,helvetica,sans-serif;" class="MsoNormal"><span lang="EN-US">Hello!</span></p>

<p style="font-family: arial,helvetica,sans-serif;" class="MsoNormal"><span lang="EN-US">When I
tried to render the sphere model with pbrt, I noticed that there was a dark
point in the resulting image, normally, this point must be illuminated. After analyzing,
I perceived that the normal vector computed on the sphere is not continuous. </span>Could anyone help me to resolve this problem?
</p><p style="font-family: arial,helvetica,sans-serif;" class="MsoNormal"><span lang="EN-US">This
is my .pbrt file and you find in attached the resulting image. <span> </span>The dark point is in the red circle. </span></p>

<p style="font-family: arial,helvetica,sans-serif;" class="MsoNormal"><span lang="EN-US"> </span></p>

<p class="MsoNormal"><span lang="EN-US"><span style="font-family: arial,helvetica,sans-serif;"> Film &quot;image&quot; &quot;string filename&quot;
 [&quot;sphere.exr&quot;]</span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
        &quot;integer xresolution&quot; [500]
&quot;integer yresolution&quot; [500] </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
   Sampler  &quot;bestcandidate&quot;
 &quot;integer pixelsamples&quot; [4] </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
   LookAt -12 -3 12 0 0 0 0 1 0     </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    Camera &quot;orthographic&quot; </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    WorldBegin    </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
   AttributeBegin </span><br style="font-family: arial,helvetica,sans-serif;">
<span style="font-family: arial,helvetica,sans-serif;">   CoordSysTransform &quot;camera&quot; </span><br style="font-family: arial,helvetica,sans-serif;">
<span style="font-family: arial,helvetica,sans-serif;">     LightSource &quot;distant&quot;  &quot;color I&quot; [ 3 3 3 ] &quot;point
from&quot; [0 0 0] &quot;point to&quot; [-1 -1 1]</span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    AttributeEnd </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    AttributeBegin</span><br style="font-family: arial,helvetica,sans-serif;">
<span style="font-family: arial,helvetica,sans-serif;">     Material &quot;plastic&quot;
&quot;color Kd&quot; [1.0 1.0 1.0] &quot;color Ks&quot; [8 8 8] &quot;float
roughness&quot; [.006] </span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    Shape &quot;sphere&quot; &quot;float radius&quot; [.3]</span><br style="font-family: arial,helvetica,sans-serif;">
<span style="font-family: arial,helvetica,sans-serif;">     AttributeEnd</span><br style="font-family: arial,helvetica,sans-serif;"><span style="font-family: arial,helvetica,sans-serif;">
    WorldEnd</span></span></p><p class="MsoNormal"><br><span lang="EN-US"><span style="font-family: arial,helvetica,sans-serif;"></span></span></p><span lang="EN-US"><span style="font-family: arial,helvetica,sans-serif;">Thanks</span></span>