3D World

Opin­ion: Gra­ham Jones

As a busy VR stu­dio, we have to cre­ate a lot of 3D mod­els very quickly – and we’ve in­creas­ingly been adopt­ing pho­togram­me­try and laser scan­ning to help. Gra­ham Jones, lead mod­eller at Im­mer­sive Stu­dios, dis­cusses tips and tech­niques

- Get in touch at info@im­mer­sivevr.co.uk or visit www.im­mer­sivevr.co.uk

Lead mod­eller at Im­mer­sive Stu­dios di­vulges tips and tech­niques for 3D mod­el­ling

Cre­at­ing both VR and AR ex­pe­ri­ences re­quires low­poly mod­els, es­pe­cially if a VR ex­pe­ri­ence is run­ning in-en­gine. And of­ten, when cre­at­ing client projects, we need to turn around high-qual­ity mod­els fast – for ex­am­ple when we needed to model the new Brab­ham BT62 hy­per­car as well as her­itage F1 cars in a short space of time. Pho­togram­me­try and laser-scan­ning of­fer us a re­ally ef­fec­tive head start – pro­vid­ing a de­tailed model that you can ei­ther use as it is, or take into a 3D ap­pli­ca­tion and re­work to make game-ready.

For pho­togram­me­try, we use a cam­era to take hun­dreds of dif­fer­ent pho­tos of an ob­ject and then use spe­cial­ist soft­ware to com­pare the match­ing pix­els be­tween the pho­tos to form a ‘point cloud’, which can then be used to cre­ate the model. Laser scan­ning is a sim­i­lar tech­nique – it in­volves fir­ing a laser onto an ob­ject which is then pro­jected back to form the point cloud, ef­fec­tively giv­ing you a work­ing model in real time.

Both tech­niques are ba­si­cally like a form of dig­i­tal shrink-wrap­ping – all the minute de­tails are al­ready there on the model. You can then project these de­tails onto a low-poly mesh, and trans­fer all the bumps, heights and small an­gles to the low poly­gon us­ing a nor­mal map. This gives us high­fi­delity, low-poly mod­els that can be run ef­fi­ciently in-en­gine with­out com­pro­mis­ing on aes­thetic qual­ity – all in less time.

Our top tips

• Pick your tar­get If you want to use pho­togram­me­try or laser scan­ning make sure you can ac­cess your ob­ject eas­ily – for ex­am­ple, it’s no good try­ing to laser scan a re­ally tall build­ing if you can’t reach the top. • Flat light­ing is best In very bright light, the cam­era will catch all the vari­a­tions in colour and the tex­ture ends up look­ing un­even, so aim for flat or grey light­ing. Also, if you try to scan any­thing with a shiny and/or black sur­face you’ll need to project a tex­ture or pat­tern over the shape so the laser doesn’t can­cel it­self. • Know your equip­ment You can use more or less any cam­era for pho­togram­me­try but laser scan­ners can be harder, and a lot more ex­pen­sive, to get hold of. The good news is you can hire them. The Artec scan­ner is usu­ally the scan­ner of choice, of­fer­ing up to 0.1mm of ac­cu­racy. On the cheaper end of the scale, you can also buy a ‘struc­ture sen­sor’ that at­taches to an iphone or an ipad, which gives you a low­erqual­ity but ef­fec­tive scan. • Make it easy for your­self For pho­togram­me­try, it’s eas­ier to move around the ob­ject as you pho­to­graph it rather than ro­tat­ing the ob­ject it­self – it just makes it eas­ier for the soft­ware to map ev­ery­thing out. When work­ing to scale, put a ruler down and in­clude that in your scan/pho­tog­ra­phy to pro­vide an ac­cu­rate ref­er­ence for mea­sure­ments when visu­al­is­ing ar­chi­tec­ture, or sim­i­lar. • En­joy the ex­tra time Pho­togram­me­try saves so much time in the mod­el­ling process. It helps en­sure a good level of de­tail and gets mod­els to ren­der faster – which is es­sen­tial for in-game VR ex­pe­ri­ences, and for eas­ing the pres­sure on tight dead­lines!

“Both tech­niques are Ba­si­cally like a form of dig­i­tal shrink-wrap­ping”

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