[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-648300-105":59,"doc-detail-648300-en":130},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":123,"head_meta":125,"extra_data":127,"updated_unix":129},105,"en","lecture-20-lods-fall-2004","Lecture 20 - LODs - Fall 2004","","Lecture 20 in the Fall 2004 Cornell CS course by Kavita Bala introduces rendering research on lighting with many lights and then transitions to Level of Detail (LOD). It motivates LOD by viewer distance, contrasting close-view detail with far-view approximations. The lecture explains standard game-style LOD models, typical issues (creation, selection, artifact-free switching), and two frame-based resolution selection strategies. It concludes with LOD switching artifacts like popping and flickering, and practical remedies such as more hierarchical resolutions and blending or morphing.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":30,"@type":76,"position":81},"https://docshare.wps.com/document/technology/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/lecture-20-lods-fall-2004/648300/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/lecture-20-lods-fall-2004/648300.png","ImageObject",300,407,{"name":92,"@type":93},"Dipper","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-27","2026-10-23",true,{"@type":102,"interactionType":103,"userInteractionCount":8},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"Why is level of detail (LOD) used in rendering?","Question",{"text":112,"@type":113},"LOD techniques draw models at different resolutions depending on relevance to the viewer: more detail up close and approximation when far away.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"What are the main issues when working with LODs?",{"text":117,"@type":113},"Key issues are LOD creation, LOD selection (choosing which model to display), and LOD switching (avoiding artifacts during transitions).",{"name":119,"@type":110,"acceptedAnswer":120},"How can LOD switching artifacts like popping and flickering be reduced?",{"text":121,"@type":113},"Solutions include using more resolutions in the hierarchy and blending two resolutions, such as image blending (draw both) or geometry blending (morph between).","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},648300,1793073638,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":29,"category_name":30,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":8,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":139,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":145},1374404997633,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Lecture 20: LODs  \nFall 2004  \nKavita Bala  \nComputer Science Cornell University  \nResearch on many lights  \n• Ward ‘91  \n• Shirley, Wang, Zimmerman ‘94  \n• Fernandez, Bala, Greenberg ‘02 • Wald and Slusallek’03  \n• Environment Map Sampling    \n© Kavita Bala, Computer Science, Cornell University  \n Rendering w/ Environment Maps • High lighting complexity  \n• Rich: captures real world  \n© Kavita Bala, Computer Science, Cornell University  \nHigh-Dynamic Range Imagery  \n• Multiple Exposures  \n© Kavita Bala, Computer Science, Cornell University  \n\n|  |  |\n| --- | --- |\n| | |\n| © Kavita Bala, Computer Science, Cornell University |  |\n\nSampling Environment Maps  \n• Say we have a fixed budget of samples  \n– Say 300 or 3000  \n• Goal: sample environment maps La ∆ ω b  \n• Basic idea: sample according to …  \n– Illumination importance sampling: oversamples small bright lights  \n– Area-based stratified sampling: distribute samples over area (under-samples bright lights)  \n© Kavita Bala, Computer Science, Cornell University  \nNew Metric  \n1  \n• Instead L∆ ω  4  \n© Kavita Bala, Computer Science, Cornell University  \nHierarchical Threshold  \n• Create regions from iσ to (i +1) σ  \n• Distribute samples in region according to metric Metric  \nN = N  j   \nj Metric map  \n• Distribute samples in each region according to Hochbaum-Shmoys  \n– Minimize maximum distance  \n© Kavita Bala, Computer Science, Cornell University  \n© Kavita Bala, Computer Science, Cornell University  \n© Kavita Bala, Computer Science, Cornell University  \nSummary  \n• Rendering with many lights remains an open problem  \n– Techniques are linear in number of lights  \n– Hard to handle visibility  \n• Some interesting new approaches needed for interactive rendering with many lights  \n© Kavita Bala, Computer Science, Cornell University  \nComplexity  \n• Lighting: many lights, environment maps  \n– Global illumination, shadows  \n• Materials: BRDFs, textures  \n• Geometry: Level-of-detail, point-based representations  \n• All: impostors, image-based rendering  \n© Kavita Bala, Computer Science, Cornell University  \nLOD  \n• What is Level of detail used for?  \n• When close, want detail  \n• When far, want approximation  \n• Level of Detail (LOD) techniques draw models at different resolutions depending on their relevance to the viewer  \n© Kavita Bala, Computer Science, Cornell University  \n\n| LOD Models (I) |  |  |  |\n| --- | --- | --- | --- |\n| | | | |\n| © Kavita Bala, Computer Science, Cornell University |  |  |  |\n\n\n| LOD Models (II) |  |  |\n| --- | --- | --- |\n| | | |\n| © Kavita Bala, Computer Science, Cornell University |  |  |\n\nLOD Models (3)  \n• Effect of LOD less obvious if smooth shaded  \n• Note also that shading changes with LOD  \n© Kavita Bala, Computer Science, Cornell University  \nStandard LOD  \n• Used in games  \n– Finite set of models  \n– Hand generated  \n– Or using automatic decimation/simplification  \n• Use of LODs: based on distance from eye or projected screen size  \n© Kavita Bala, Computer Science, Cornell University  \nIssues with LODs  \n• LOD Creation  \n• LOD Selection: Choosing which model to display  \n• LOD Switching: Artifact-free switching between LODs  \n© Kavita Bala, Computer Science, Cornell University  \nSelecting LOD Models  \n• For any given frame, decide what resolution to display  \n• Option 1: Choose each object’s resolution independently  \n– For example, use projected area or distance  \n– The current standard practice: fast, simple  \n– Potential problem: total \\# polygons may be large  \n• Option 2: Fix number of polygons and choose models to fit in budget  \n– Ensures near constant frame rate, but harder to implement  \n© Kavita Bala, Computer Science, Cornell University  \nLOD Switching  \n• Popping when models switched  \n• Popping is visually disturbing  \n– Why?  \n– Flickering when at threshold  \n• Solutions:  \n– Have more resolutions in hierarchy  \n– Blend two resolutions  \n􀂃 Image blend: draw both resolutions  \n􀂃 Geometry blend: morph between resolutions  \n© Kavita ","cbCaidY5IRulwsM0","https://ap.wps.com/l/cbCaidY5IRulwsM0","pdf",816868,14,"English","# Rendering with Environment Maps\n## Sampling Environment Maps\n## New Metric and Hierarchical Threshold\n## Summary: Many-Lights Rendering Complexity\n# Level of Detail (LOD)\n## Purpose of LOD\n## LOD Models\n## Standard LOD in Games\n## Issues with LODs\n## Selecting LOD Models\n## LOD Switching","[{\"question\":\"Why is level of detail (LOD) used in rendering?\",\"answer\":\"LOD techniques draw models at different resolutions depending on relevance to the viewer: more detail up close and approximation when far away.\"},{\"question\":\"What are the main issues when working with LODs?\",\"answer\":\"Key issues are LOD creation, LOD selection (choosing which model to display), and LOD switching (avoiding artifacts during transitions).\"},{\"question\":\"How can LOD switching artifacts like popping and flickering be reduced?\",\"answer\":\"Solutions include using more resolutions in the hierarchy and blending two resolutions, such as image blending (draw both) or geometry blending (morph between).\"}]","Lecture 20 - LODs - Fall 2004 | PDF",1792793021,35]