Photographing textures for 3D computer-generated visualizations

V 3D-prostoru uporabljamo teksture in mape za doseganje naravnega izgleda scene. Eden izmed načinov pridobivanja tekstur je fotografiranje. Če barvnim teksturam v 3D-prostoru dodamo še mape, dobimo boljši rezultat. V diplomskem delu je bilo raziskano področje teksturiranja, fotografiranja tekstur in priprave map za uporabo v 3D računalniško generiranih vizualizacijah. Teksture so bile fotografirane s fotoaparatom Nikon D7000 z objektivom 18–105 mm. Zbranih je bilo dvanajst fotografij tekstur: tri teksture vrat, tri oken in šest sten. Fotografije so bile nato urejene v programu Photoshop, tu so bile narejene tudi »bump« mape (sivinske mape, ki površini dodajo navidezno višino ali vdolbino). Za izdelavo map normal (RGB-slike, ki simulirajo geometrijo v vseh treh smereh X, Y in Z) je bil uporabljen program CrazyBump. 3D-scena je bila postavljena v programu Autodesk Maya. Za vsako izmed tekstur so bile narejene tri upodobitve (ang. Renders): (1) upodobitev modela samo z barvno teksturo, (2) modela z barvno teksturo in (3) »bump« mapo ter modela z barvno teksturo in mapo normal. Izvedena je bila anketa, pri kateri so anketiranci ocenjevali razlike pri vseh treh kombinacijah upodobitev: (1) model z barvno teksturo v primerjavi z modelom z mapo normal, (2) model z barvno teksturo v primerjavi z modelom z »bump« mapo in (3) model z mapo normal v primerjavi z »bump« mapo. Razlike so ocenjevali glede na štiri kategorije: reliefnost, kontrast, barve in prostornost. Največje razlike so bile ocenjene pri primerjavi modela z »bump« mapo, vendar pa je bila tu večkrat najvišje ocenjena razlika v kontrastu in barvi, kar pa ni to, kar želimo z »bump« mapo doseči. Iz tega sklepamo, da »bump« mapa ustvari nekoliko nenaraven videz in je zaradi tega tudi najbolj očitna. Mapa normal pa je manj očitna, saj zgleda bolj naravno. Rezultati eksperimentalnega dela so torej pokazali, da je za primere tekstur, ki so bile uporabljene v tej raziskavi, v splošnem najbolje uporabiti mapo normal, saj nam da najbolj naraven izgled reliefnosti.In 3D space we use textures and maps to achieve a natural look of the scene. One of the ways to get textures is photography. If we add maps to the colour textures in 3D space, we get an even better result. In this thesis, texturing, photographing textures and preparation of maps for use in 3D computer generated visualizations, were explored. The textures were photographed with the Nikon D7000 camera with a 18–105 mm lens. Twelve photographs of textures were chosen: three textures of doors, three of windows and six of walls. The photographs were then edited in Photoshop and bump maps (grayscale maps, which add simulated height or depth to a model’s surface) were made. Normal maps (RGB images, which simulate geometry in all tree directions X, Y and Z) were generated in the program CrazyBump. 3D scene was created in Autodesk Maya. Three renders were made for each of the textures: (1) render of a model with only colour texture, (2) a model with colour texture and bump map and (3) a model with colour texture and normal map. A survey was made, where differences between renders were evaluated: (1) model with colour texture versus model with normal map, (2) model with colour texture versus model with bump map and (3) model with normal map versus model with bump map. The differences were evaluated based on four criteria: relief, contrast, colour and spaciousness. The biggest differences were determined when comparing the model with a bump map to other two. However, the biggest differences were determined in contrast and colour, which is not what we want to achieve with a bump map. From that we can conclude, that a bump map creates a slightly unnatural look and that is also why it is most obvious. A normal map is less obvious because it looks more natural. Results of the experimental part have shown, that for the textures, which were used in this thesis, it is best to use a normal map, which gives the most natural look of relief