Master med­i­cal visu­al­i­sa­tion

Learn the best way to ren­der med­i­cal vi­su­al­i­sa­tions us­ing X-par­ti­cles and Cin­ema 4D with art di­rec­tor Farid Ghanbari

3D Artist - - CONTENT -

Top tech­niques from Farid Ghanbari

This tu­to­rial will teach you how to cre­ate a med­i­cal visu­al­i­sa­tion in the 3d world. Be­fore start­ing the project, we need to gather some ref­er­ences to make sure that the sizes of the cells are sci­en­tif­i­cally ac­cu­rate. We will use cin­ema 4d and X-par­ti­cles as our main tools to set up the scene and learn how to use X-par­ti­cles to quickly cre­ate hun­dreds of sperm in a nice shape with­out deal­ing with each in­di­vid­ual one. v-ray will then be utilised to light the sperms and egg with its pow­er­ful sub­sur­face scat­ter­ing ma­te­rial.


Choose the sub­ject the most im­por­tant pur­pose of a true med­i­cal illustration is to ed­u­cate the viewer. it must be clear and sci­en­tif­i­cally ac­cu­rate, pay­ing care­ful at­ten­tion to good de­sign, or­gan­i­sa­tion of con­tent and where you are lead­ing the eye. it also pro­vides us with a vast ar­ray of sub­jects that we wouldn’t nor­mally con­sider il­lus­trat­ing. the real-life mi­cro­scopic en­vi­ron­ments that ex­ist in our own bod­ies can pro­vide in­spi­ra­tion for imag­i­na­tive land­scapes.


Cre­ate the egg to start the art­work, we need a nice egg shape as a base. Make a sim­ple sphere in cin­ema 4d and change the type from stan­dard to Hex­a­he­dron to get an even dis­place­ment over the en­tire egg. to add the de­tails, you can eas­ily put a dis­placer de­former and add a c4d­noise to its shader tag. Play with the noise type to get your de­sired de­tails. You can also use lay­ers and mask your first noise with a sec­ond one. sharper de­tails need more seg­ments in your sphere pa­ram­e­ters.


Make the sperm since we have so many sperm, we need a way to cre­ate them in­stantly. X-par­ti­cles al­lows us to do that eas­ily. First, we need an emit­ter and an xp­trail to see the emit­ter paths. sec­ond, we need an xp­fol­low­sur­face mod­i­fier to con­duct par­ti­cles to the egg. Play with the dis­tance and pull to get your de­sired form. We can also play with vari­a­tion to add a lit­tle vari­a­tion to it and make it more nat­u­ral. spend enough time at this level and en­sure that you are get­ting the best re­sult.


Work with xp­splinemesher once we get the nice fol­low path, we can start shap­ing the ac­tual form of the sperm. thank­fully, we don’t need to deal with poly­gon mod­el­ling to do that and here you will see the power of the X-par­ti­cles plugin. Just put an xp­splinemesher and set your xp­trail as its source. it will cre­ate the ge­om­e­try in­stantly. From here, we just need to tweak the set­ting and play with the splinemesher spline curve to shape the sperm. You can fol­low your ref­er­ence out­line and play with spac­ing value and sub­di­vi­sions to get the best re­sult.


Add a lit­tle art to the science Be­cause we are cre­at­ing art­work in­spired by science, rather than a purely in­struc­tional med­i­cal illustration, we want to go a lit­tle fur­ther and make it more in­ter­est­ing. of course, sperm in real world have a de­fined tail length but to cre­ate some nice de­tails with thou­sands of tan­gled sperm tails, we can ex­tend this. We can stop it wher­ever we want by set­ting dif­fer­ent val­ues on the life­span on the emit­ter.


Cre­ate mood for the en­vi­ron­ment in­side a real body, bi­o­log­i­cal pro­cesses hap­pen in to­tal dark­ness, but that isn’t very in­ter­est­ing. our med­i­cal-in­spired art­work needs an en­vi­ron­ment that we can re­late to. Here, to cre­ate this mood the best op­tion is the en­vi­ron­ment fog but to have a bet­ter con­trol of it we need to cre­ate a Fog Box to con­trol the amount of fog and its depth on the hero as­set. this will give your ren­der­ing a nice depth and pull out your main hero to re­ally em­pha­sise it.


Sec­ondary sperm as you may know, not all sperm reach the egg and there will still be a lot of them swimming in the fal­lop­ian tube af­ter fer­til­i­sa­tion hap­pens. By hav­ing those sec­ondary sperm, not only can we make our art­work a lit­tle more sci­en­tif­i­cally ac­cu­rate, but we can also bring more depth to it and make a bet­ter com­po­si­tion. so ac­cord­ing to our cam­era, we can put a few sperm pretty close to the cam­era to make an in­tense dof, and put some far away be­hind the egg so that they will be out of fo­cus but still we can see them.


Start the light­ing to start the light­ing, it’s best to as­sign a v-ray ad­vanced ma­te­rial and leave it on the de­fault set­ting. We don’t want to mess with the ma­te­ri­als at this stage. this helps you fo­cus just on lights and make a bet­ter de­ci­sion. some­times dif­fer­ent colours, re­flec­tion and spec­u­lar can be dis­tract­ing and slow down the light­ing process. as the first step, we just put a v-ray dome light with low in­ten­sity to see the whole scene with even light­ing and no harsh shad­ows.


Key light, dif­fer­ent ex­pe­ri­ence the ma­jor­ity of the egg and sperm will be il­lu­mi­nated by the key light and so this light has the most crit­i­cal role in our light­ing. spend enough time play­ing with dif­fer­ent an­gles and moods. set your ren­der sam­pling to pro­gres­sive with a low-res­o­lu­tion im­age size to have some quick test ren­ders that you can com­pare with. We can also try var­i­ous di­rec­tional num­bers in the v-ray light to have dif­fer­ent bright­ness and harsh­ness of shad­ows.


Vol­ume light the fog doesn’t work by it­self but the com­bi­na­tion of the fog and one vol­ume light could make a stun­ning back­ground. to es­tab­lish that, cre­ate a v-ray spot light and put it be­hind the egg. You can keep play­ing with this to achieve the best re­sults. in­ner and outer an­gles play the big­gest roles in get­ting a nice gra­di­ent in the back­ground. You can also add a lit­tle bluish or green­ish tint to your light to make it more in­ter­est­ing.


The colour palette once we get a de­cent ba­sic re­sult with our light­ing on a sim­ple grey ma­te­rial, we need to as­sign colours to see how it works. at this stage, we rec­om­mend that you add sss to your ma­te­ri­als, since it af­fects the light­ing a lot. You can play with the sim­ple colours to get your de­sired colour palette, then cre­ate de­tails like bumps, dis­place­ments and dirt. Be­cause we are do­ing a science-in­spired project in­stead of a truly sci­en­tif­i­cally ac­cu­rate illustration, we can let our imag­i­na­tions run wild with crazy colour schemes. But know­ing what colours your sub­ject would have in the real world can help cre­ate your palette, and this will make your art­work more con­sis­tent and easy to read.

Be­cause we are do­ing a science-in­spired project in­stead of a truly sci­en­tif­i­cally ac­cu­rate illustration, we can let our imag­i­na­tions run wild


Rim light When you use sub­sur­face scat­ter­ing Ma­te­ri­als, the rim light is one of the key fac­tors to work on, just like the key light. sss ma­te­ri­als use the lights that come in­side them from the op­po­site side of cam­era an­gle so try to put these in the best po­si­tions to achieve the most sat­is­fy­ing scat­ter­ing ef­fect. You may need to play with sss pa­ram­e­ters such as scat­ter­ing ra­dius, sub­sur­face colour and over­all colour at the same time. don’t for­get to try dif­fer­ent tint colours on your rim light.


Fi­nal tune at light­ing You will al­ways need to redo some work dur­ing the process, whether it be tex­tures colours, lights or even slight changes to the mod­els and po­si­tion­ing, and this is com­pletely nor­mal. at this stage, look over your ren­der­ing and try to just tweak it to get the most sat­is­fy­ing re­sult from your vi­sion. turn your lights on and off sep­a­rately to see how they work with your scene.


Set up the ren­der set­ting thank­fully, v-ray for cin­ema 4d has made ev­ery­thing a lit­tle eas­ier for users – you just need to take the most care with your sam­pling. For this ren­der, use Bucket type for sam­pler with 0.004 thresh­old. set the Max sub­di­vi­sion to 100 and put the Min to 0. don’t for­get to en­able am­bi­ent oc­clu­sion, which comes un­der in­di­rect il­lu­mi­na­tion. since we have cre­ated a v-ray Fog Box, you don’t need to turn on the en­vi­ron­ment fog in your en­vi­ron­ment tab.


Ren­der passes to cre­ate your ren­der passes in v-ray for cin­ema 4d, you need to open the v-ray mul­ti­pass Man­ager win­dow from the main v-ray Bridge tab. se­lect your de­sired passes and make sure that they are all checked. now you just need to add a post-ef­fects pass on the mul­ti­pass menu in your cin­ema 4d ren­der set­ting win­dow. Here we have cre­ated dif­fer­ent ob­ject id and the Z-depth pass to have more con­trol at post-pro­duc­tion stage.


Ap­ply DOF With­out depth of field, we would have a bor­ing, flat im­age. in the real world, we would only be able to see these tiny cells through a mi­cro­scope. Mi­cro­scopes have a very shal­low depth of field so in homage to that, us­ing depth of field as in­tensely as pos­si­ble can help rep­re­sent that. Here we have used lenscare’s Frischluft plugin in af­ter ef­fects to achieve a nice depth of field. But no mat­ter what soft­ware you pre­fer to use, since you have an ac­cu­rate Zdepth pass, you can use it in which­ever ap­pli­ca­tion you hap­pen to be most com­fort­able with.


Post-pro­duc­tion since we did the most of the ren­der­ing in-pack­age and we now have a nice-look­ing re­sult, we may need to do just a lit­tle colour cor­rec­tion but there are no big changes in post-pro­duc­tion. the only things we will add to our im­age at this fi­nal stage are the clouds. For this, you can sim­ply find some PNG files on­line and put them close to the egg. Be­sides mak­ing your ren­der­ing more artis­tic, they will give an un­ex­pected sense of scale to sur­prise and de­light your au­di­ence.



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