{"id":324,"date":"2024-07-13T15:27:39","date_gmt":"2024-07-13T13:27:39","guid":{"rendered":"https:\/\/cammonte.com\/?page_id=324"},"modified":"2024-07-15T15:05:10","modified_gmt":"2024-07-15T13:05:10","slug":"nori-an-educational-ray-tracer","status":"publish","type":"page","link":"https:\/\/cammonte.com\/index.php\/nori-an-educational-ray-tracer\/","title":{"rendered":"Nori: An educational ray tracer"},"content":{"rendered":"\n

As part of the Advanced Computer Graphics class<\/a>, taught by Prof. Dr. Wenzel Jakob at EPFL<\/a>, I worked on Nori: a minimalist ray tracer written in C++. The objective of the class was to lay the groundwork for an effective renderer by implementing its core features<\/strong>. We built on top of the Nori base code, which includes many pre-built components that would be laborious to create from scratch, such as a simple GUI for real-time image rendering, an XML-based scene file loader, and basic geometric primitives classes. Below are the various topics covered in the course and the corresponding features I implemented in the renderer.<\/p>\n\n\n\n

TL;DR<\/h3>\n\n\n\n

I implemented the core features of a renderer written in C++, including:<\/p>\n\n\n\n

    \n
  • Ray tracing acceleration data structures<\/li>\n\n\n\n
  • Basic rendering algorithms: whitted-style, path tracer with multiple importance sampling<\/li>\n\n\n\n
  • Homogeneous participating media<\/li>\n\n\n\n
  • Light and materials modelisation<\/li>\n\n\n\n
  • Textures and normal mapping<\/li>\n<\/ul>\n\n\n\n

    Ray tracing acceleration data structures<\/h1>\n\n\n\n

    I implemented an octree<\/strong>, a hierarchical data structure designed to expedite ray intersection computations with large numbers of triangles. This step involved constructing the octree, optimising its data organisation for efficient memory usage<\/strong>, and sing it for ray tracing by performing an ordered traversal <\/strong>of the tree’s children from nearest to farthest.<\/p>\n\n\n\n

    I also focused on performance optimisation<\/strong>, employing the parallelisation<\/strong> abilities to enhance the efficiency and speed of the implementation.<\/p>\n\n\n\n

    Monte Carlo sampling<\/h1>\n\n\n\n

    I implemented Monte Carlo sampling techniques<\/strong> to transform an initially uniform distribution into various target distributions. This involved computing and implementing both the distribution functions and the corresponding sample warping schemes.<\/p>\n\n\n\n

    This gave me a first hands-on experience in probabilistic modeling and numerical methods<\/strong>.<\/p>\n\n\n\n

    Basic rendering algorithms<\/h1>\n\n\n\n

    I implemented several basic rendering algorithms<\/strong> including:<\/p>\n\n\n\n

      \n
    • Ambient occlusion<\/strong>, a rendering technique that assumes that a surface receives uniform illumination from all directions and that visibility is the only effect that matters.<\/li>\n\n\n\n
    • Whitted-style ray-tracer<\/strong>, which integrates the incident radiance by sampling points on a set of light sources and is able to account for specular reflections and refractions.<\/li>\n\n\n\n
    • Path tracer with Multiple Importance Sampling<\/strong>, which enhances accuracy and efficiency by weighting the contributions from different sampling techniques based on their effectiveness in capturing various lighting scenarios.<\/li>\n<\/ul>\n\n\n\n
      \n
      \n
      \"\"
      Rendered using multiple importance sampling<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n\n
      \n
      \"\"
      Rendered using multiple importance sampling<\/strong><\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n

      Homogeneous participating media<\/h1>\n\n\n\n

      I added to the renderer support for handling homogeneous participating media (media with constant density and scattering properties), mainly in order to render beams of light.<\/p>\n\n\n\n

      \"\"<\/figure>\n\n\n\n

      Light and materials modelisation<\/h1>\n\n\n\n

      Throughout the project, I implemented various models of light sources and materials to be used to render interesting things and validate my other implementations.<\/p>\n\n\n\n

      Light sources<\/h2>\n\n\n\n
        \n
      • Point lights<\/li>\n\n\n\n
      • Area lights<\/li>\n\n\n\n
      • Specialised emitters (rectangular, spherical, and disk lights)<\/li>\n\n\n\n
      • Image-based lighting<\/li>\n<\/ul>\n\n\n\n

        BRDFs<\/h2>\n\n\n\n
          \n
        • Dielectric<\/li>\n\n\n\n
        • Microfacet<\/li>\n\n\n\n
        • Thin dielectric<\/li>\n\n\n\n
        • Mirror<\/li>\n<\/ul>\n\n\n\n
          \n
          \n
          \"\"
          Thin dielectric and dielectric spheres<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n\n
          \n
          \"\"
          Microfacet bowl<\/strong><\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n

          Textures and normal mapping<\/h1>\n\n\n\n

          I ultimately added to the renderer a few “low-effort” features to be able to model more realistic looking scenes, notably the Ability to add textures<\/strong> and normal maps<\/strong> to the different meshes in the scene with different simple types of UV mapping.<\/p>\n\n\n\n

          \n
          \n
          \"\"
          Texture mapped on a sphere<\/strong><\/figcaption><\/figure>\n<\/div>\n\n\n\n
          \n
          \"\"
          Normal map and texture mapped on a sphere<\/strong><\/figcaption><\/figure>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

          As part of the Advanced Computer Graphics class, taught by Prof. Dr. Wenzel Jakob at EPFL, I worked on Nori: a minimalist ray tracer written in C++. The objective of the class was to lay the groundwork for an effective renderer by implementing its core features. We built on top of the Nori base code, […]<\/p>\n","protected":false},"author":1,"featured_media":445,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"ub_ctt_via":"","site-container-style":"default","site-container-layout":"default","site-sidebar-layout":"default","disable-article-header":"default","disable-site-header":"default","disable-site-footer":"default","disable-content-area-spacing":"default","footnotes":""},"class_list":["post-324","page","type-page","status-publish","has-post-thumbnail","hentry"],"featured_image_src":"https:\/\/cammonte.com\/wp-content\/uploads\/2024\/07\/mis.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/pages\/324","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/comments?post=324"}],"version-history":[{"count":29,"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/pages\/324\/revisions"}],"predecessor-version":[{"id":539,"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/pages\/324\/revisions\/539"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/media\/445"}],"wp:attachment":[{"href":"https:\/\/cammonte.com\/index.php\/wp-json\/wp\/v2\/media?parent=324"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}