Part I: Adjusting the GI settings
Langkah 1. pertama membuat1.1. Buka adegan (yang dapat ditemukan
di sini).1.2. Menetapkan V-Ray sebagai penyaji saat ini.Karena
standar V-Ray pengaturan yang sangat tidak cocok untuk preview awal
yang cepat, kami akan membuat penyesuaian beberapa cepat sebelum
render pertama.1.3. Periksa opsi Override mtl dalam peluncuran
switch Global, klik tombol sebelahnya dan pilih bahan VRayMtl
default.1.4. Menetapkan jenis Citra sampler untuk tetap.1.5.
Mengatur resolusi 400 x 325 untuk.1.6. Mengatur ukuran Region dalam
peluncuran Sistem untuk 32 32 piksel.1.7. Opsional, Anda dapat
mengaktifkan cap Bingkai untuk mencetak waktu render pada
gambar.
1.8. Render Adegan:Langkah 2. GI pratinjau2.1. Belok GI dari
peluncuran pencahayaan tidak langsung.2.2. Pilih peta Cahaya baik
sebagai mesin GI primer dan sekunder.2.3. Dalam peluncuran tembolok
Cahaya, mengatur subdivs ke 500, karena kita hanya menginginkan
preview cepat. Kami akan kembali ini sampai 1000 untuk rendering
akhir.2.4. Mengatur interp tersebut. sampel dari peta cahaya untuk
5 untuk rendering lebih cepat.2.4. Mengaktifkan opsi Tampilkan fase
calc untuk peta cahaya.2,5. Render:
Hasilnya cukup berisik, tetapi tidak memberikan ide yang baik
dari apa pencahayaan adegan seperti.Langkah 3: Tweaks3.1. Karena
adegan terlihat terlalu gelap, kami ingin mencerahkan itu sedikit.
Ada beberapa cara untuk melakukan hal ini. Salah satunya adalah
untuk meningkatkan kekuatan lampu. Namun, ini akan membuat daerah
langsung menyala dari gambar, seperti patch sinar matahari, terlalu
terang, sementara daerah tidak langsung menyala akan tetap relatif
gelap. Berikut adalah contoh dari ini (semua lampu x 2):
Anda dapat melihat bahwa kekuatan cahaya meningkat telah membuat
terang gambar, dan juga telah meningkatkan kontras pencahayaan.
Adegan masih terlihat gelap meskipun. Kita dapat meningkatkan
kekuatan cahaya lebih jauh, tetapi ini akan meniup daerah langsung
menyala terlalu banyak, dan akan memperlambat perhitungan GI nanti.
Jadi, bukannya meningkatkan kekuatan cahaya, kita hanya akan
membuat cerah materi.3.2. Pergi ke Edtior Material dan menempatkan
VRayMtl default di salah satu slot (itu muncul sebagai yang
digunakan dalam "Lingkungan" di browser Bahan / Maps).3.3. Membuat
buram warna dari bahan RGB (200.200.200).3.4. memberikan
Hasilnya jauh lebih baik. Kami masih memiliki jumlah yang sama
dari cahaya yang masuk TKP, tetapi melambung sekitar lebih dan
dengan demikian meningkatkan kecerahan keseluruhan adegan.Pada
titik ini, Anda dapat menyesuaikan rasio, dll warna lampu,
sementara mendapatkan umpan balik yang relatif cepat pada
pencahayaan.Langkah 4. Lebih baik GI.Pengaturan GI yang kita
gunakan baik sebagian besar untuk preview cepat, sementara Anda
masih menyesuaikan adegan. Setelah Anda telah menetap di parameter
lampu, saatnya untuk memperbaiki solusi GI.4.1. Tetapkan mesin GI
utama untuk radiasi peta.4.2. Pilih preset Sedang untuk peta
radiasi.4.3. Putar calc Tampilkan opsi fase untuk peta radiasi
pada.4.4. Render adegan.Rendering membutuhkan lebih banyak waktu
sekarang sebagai V-Ray perlu menghitung solusi GI lebih tepat.
Langkah 5: antialiasing yang lebih baik dan kurang kebisinganThe
GI terlihat ok sekarang, tapi kami masih memiliki antialiasing
tidak ada dan ada kebisingan dari area cahaya di jendela. Kami akan
berurusan dengan yang sekarang.5.1. Menetapkan jenis Citra sampler
untuk Adaptive DMC.5.2. Matikan GI off.5.3. memberikan
Kami telah antialiasing sekarang, tapi kebisingan bahkan lebih
buruk. Kami akan menyesuaikan sampler DMC untuk memperbaiki
itu.5.4. Mengatur Min. sampel sampler DMC ke 16 dan ambang
Kebisingan ke 0,002.5.5. Render.
Kebisingan kurang, namun masih ada sebagian. Mengurangi ambang
Kebisingan dan meningkatkan Min. sampel lagi tidak akan membantu.
Kita hanya perlu lebih banyak sampel untuk area cahaya. Salah satu
cara untuk melakukannya adalah untuk pergi ke parameter VRayLight
dan meningkatkan subdivs. Namun, jika Anda memiliki banyak lampu
dalam adegan, ini cukup banyak mengklik. Sebaliknya, kita akan
menggunakan subdivs Global untuk melakukan itu.5.6. Mengatur
subdivs global menjadi 4,0 dan membuat:Masih ada beberapa
kebisingan, tapi kami bisa terus meningkatkan subdivs Global sampai
hasilnya cukup baik, 16,0 tampaknya menjadi nilai yang baik.5.7.
Mengatur subdivs Global 16,0 dan membuat:Langkah 6. Final rendering
dengan GIGlobal meningkat subdivs multiplier mempengaruhi peta
radiasi juga, jadi jika kita membuat sekarang dengan GI, maka akan
terlalu lambat. Kita harus melakukan beberapa penyesuaian.6.1.
Hidupkan GI on.6.2. Mengatur subdivs Hemispheric untuk peta radiasi
menjadi 8,0 untuk mengkompensasi subdivs peningkatan global.6.3.
memberikan
Ini melengkapi bagian pertama dari tutorial. Pada bagian
berikutnya, kita akan menambahkan bahan adegan.Bagian II: Rendering
dengan bahan________________________________________Langkah 1.
Rendering dengan bahan1.1. Putar pilihan Override mtl dalam
peluncuran switch off global.1.2. Nyalakan batas refleksi /
refraksi kedalaman Max dalam peluncuran yang sama.1.3. Matikan GI
off.1.4. Mengatur treshold Kebisingan dari sampler DMC ke 0,005
untuk preview lebih cepat.1.5. Render.
Langkah 2. Preview bahan dengan GI pada2.1. Hidupkan GI on.2.2.
Untuk preview lebih cepat menetapkan mesin utama untuk cache
cahaya.2.3. memberikan
Pada titik ini Anda dapat menyesuaikan bahan adegan Anda
sementara mendapatkan preview cepat bagaimana akan terlihat dalam
adegan.Langkah 3. Lebih baik GI dengan bahan3.1. Tetapkan mesin
utama untuk radiasi peta.3.2. Mengatur ambang Kebisingan DMC ke
0,002.3.3. Mengatur subdivs cache cahaya sampai 1000.3.4. Mengatur
ukuran cache Contoh cahaya untuk 0,03 (ini akan membuat cache
cahaya sedikit lebih halus dan sedikit lebih cepat).3.4.
Render.
Ini adalah gambar terakhir yang kita akan membuat pada res penuh
di bagian berikutnya.Bagian III: Rendering gambar
akhir________________________________________Kami sekarang harus
membuat gambar akhir.Langkah 1. Menyesuaikan V-Ray untuk resolusi
yang lebih besar1.1. Mengatur resolusi untuk 1600 x 1300.1.2.
Mengatur ukuran wilayah render sampai 64 x 64.Kita akan perlu untuk
menyesuaikan parameter peta radiasi: karena kita meningkatkan
resolusi dua kali, kita dapat mengurangi Min peta radiasi dan
tingkat Max dengan 2.1.3. Mengatur peta radiasi preset ke
Custom.1.4. Mengatur tingkat radiasi peta min ke -5.1.5. Set
irradiance peta tingkat max ke -3.Langkah 2. Rendering gambar
akhir.2.1. Mengatur 3dsmax untuk menyimpan gambar yang diberikan.
Untuk presisi meningkat, Anda dapat memilih format 16-bit gambar
(misalnya, 16-bit. Png). Opsional, Anda dapat menyimpan ke gambar
hdr,. Dalam hal ini Anda perlu memilih channel warna Unclamped
dalam peluncuran GBuffer V-Ray.2.2. Tekan tombol Render.2.3. Pergi
keluar untuk makan siang.Adegan akhir untuk rendering ini dapat
ditemukan di sini.Bagian IV: Post-pengolahan
gambar________________________________________Gambar terlihat ok,
tetapi dalam kebanyakan kasus, Anda akan ingin menjadi sedikit
lebih gelap atau lebih terang sedikit dll Alih-alih mengubah lampu
dan re-render, Anda dapat melakukan penyesuaian dalam program
pengolahan citra.Sebagai contoh, di sini adalah gambar yang sama
dengan nilai gamma disesuaikan. Saya menggunakan sebuah file png
dan IrfanView untuk tujuan ini, tetapi Anda dapat menggunakan
perangkat lunak lain yang Anda merasa nyaman dengan -. Misalnya,
HDRShop untuk file hdr..Untuk menambahkan merasa lebih fotografi
untuk gambar Anda, Anda dapat menerapkan beberapa radial
penggelapan sudut, misalnya seperti ini:Displacement MappingSearch
Keywords: displacement, displacement mapping, 2D, 3DIn this
tutorial we'll examine displacement mapping in V-Ray. We will
concentrate on the 3d displacement mapping method.What is
displacement mapping?Displacement mapping is a technique for adding
geometric detail to surfaces at render time. In contrast with bump
mapping, which works by just changing the surface normal to create
the illusion of surface detail, displacement mapping modifies the
surface itself. Here is an example of the same object rendered with
bump mapping and with displacement mapping:
Original object
Bump mapping
Displacement mapping
In the case of displacement mapping, the surface is actually
modified, which leads to correct outline, shadow and GI. In the
case of bump mapping, although the surface appears modified, the
outline and the shadow stay the same.Note that displacement is
different from other kinds of shading, since it needs to modify the
actual object surface. Therefore an object must be displaced before
it can be rendered. This is why in V-Ray displacement is
represented with a modifier (although the modifier can take the
displacement map from the object material).A simple example - a
displaced sphereStart with an empty scene. Create a GeoSphere with
a radius about 40 units in the viewport and choose V-Ray as the
renderer. Apply some Standard material to the sphere.Applying the
VRayDisplacementModGo to the Modify panel and apply a
VRayDisplacementMod to the sphere. If you render straight away, you
will notice a slight displacement effect, like so:
This is because V-Ray applies a simple noise displacement map
when no other texture is chosen.Selecting a displacement mapTo
select another map, click the texture button in
VRayDisplacementMod. This will bring up the Material/map browser
dialog. Choose a Cellular texture. To edit the newly created map,
open the Material Editor and drag the map from the button in
VRayDisplacementMod to a slot in the Material Editor. Choose the
Instance method when you drop the map.If you render again, you
should get a similar result:
Setting the displacement amount and shiftTo make the
displacement effect more pronounced, increase the Amount value of
VRayDisplacementMod. If you set it to 5.0 and render you will get
something like this:
The Amount value determines the maximum displacement amount
(which occurs at places where the displacement map is white).You
can shift the whole displacement map up and down by adjusting the
Shift parameter. The effect will be to expand (for positive Shift
values) or shrink (for negative Shift values) the displaced
surface. Here are some examples of different Shift values:
Shift = -5.0
Shift = 0.0
Shift = 5.0
Note that the Shift parameter is an absolute value in world
units. If you change the Amount, you will probably need to adjust
the Shift too.Clipping geometry using the Water levelThe Use water
level and Water level parameters allow you to clip parts of the
object. Return the Shift value to 0.0, if you have changed it. Then
turn on the Use water level option and set the Water level to
2.5:
The geometry is clipped away for those places in the
displacement map where the displacement value is below the Water
level. Here are a few examples of different Water levels (assuming
the Amount parameter is still 5.0 and the Shift parameter is
0.0):
Water level = 0.0 (no clipping)
Water level = 1.25
Water level = 2.5
Water level = 3.75
Water level = 5.0 (all geometry is clipped)
The Water level parameter is also absolute in world units. If
you change the Amount and/or Shift, you will probably need to
adjust the Water level to get the same effect.For 3d displacement,
the geometry is clipped on a sub-triangle basis - a subtriangle is
either clipped away entirely, or completely visible (this is not
the case for 2d displacement where clipping is more precise).
Therefore, you may get a jagged effect at the clipped edges. You
can reduce this effect by producing more subtriangles (see the next
section).Displacement qualityV-Ray does 3d displacement by
subdividing each triangle of the original object into a number of
subtriangles. More subtriangles mean better displacement, but will
also take more memory and will increase the render time. To get a
better idea of how many subtriangles you have, apply a Standard
material to the sphere (if you haven't done so already) and turn
its Faceted option on. This is important, as otherwise V-Ray will
not only smooth the surface normals, but will also automatically
apply a normals map that represents the normal of the perfect
displaced surface, which will make the surface look a lot more
detailed that it actually is. Also, switch off the Use water level
option of VRayDisplacementMod, if it is on. If you render, you
should get a similar result (click the image for a larger
view):
Here is a blow-up of this rendering to better show the
individual subtriangles (click the image for a larger view):
In addition, here is a rendering that shows the boundaries of
the original triangles of the sphere. To do that, put a
VRayEdgesTex map in the Diffuse slot of the material and instance
this map into the Self-illumination slot. Set the Color of the
edges in the VRayEdgesTex to red and the Thickness to World
units:
The quality of the displacement is determined by the size and
number of the subtriangles. The main parameter to tweak is the Edge
length. It determines the maximum length of a subtriangle's edge.
This can be in world units or in pixels, depending on the
View-dependent option. Lower values for Edge length mean smaller
triangles and better quality. Here is the previous image rendered
with various values for Edge length (with View-dependent turned
on). Note that the View-dependent option refers to pixels in the
original image, not the zoomed-in image you get with a blow-up
rendering. This is why we were able to do a blow-up rendering to
see the individual subtriangles better. Click the images for a
larger view:Edge length value0.5Normal rendering
Blowup rendering
Edge length value1.0Normal rendering
Blowup rendering
Edge length value2.0Normal rendering
Blowup rendering
Edge length value5.0Normal rendering
Blowup rendering
Edge length value10.0Normal rendering
Blowup rendering
Search Keywords: PPT, Light CacheGeneral
In this tutorial we will discuss an alternative method for
computing the final image with V-Ray called progressive path
tracing.Typically, computing the image goes through several
separate tasks - for example, caustics calculations, light cache
computation, irradiance cache computation, and final image
sampling. While the user receives visual feedback through some of
these stages, the final image is completed only at the end of the
last stage - the intermediate results cannot be used.Progressive
path tracing, on the other hand, is a method for incremental
computation of the whole image at once. The user can stop the
calculation at any time and use the intermediate results, if they
are good enough. In addition, with path tracing, the user has only
a few controls to worry about and it is very easy for set up.V-Ray
builds upon the foundation of the light cache algorithm to perform
progressive path tracing. This has the advantage of using the light
cache for noise reduction during the path tracing process for
cleaner results and faster light propagation. Using the light cache
ensures that the number of light bounces is not limited and that
the result converges to the correct lighting solution for the
scene. In addition, the light cache from a path traced image can be
saved and re-used later on for a normal rendering.Initial
rendering
Step 1: Initial setup.Setting up progressive path tracing is
fairly easy:1.1. Open the starting scene, which can be found
here.1.2. Set V-Ray as the current rendering engine.1.3. Check the
Override mtl option in the Global switches rollout, click the
button next to it and select a default VRayMtl material.1.4. Turn
Indirect illumination on and set both the primary and the secondary
GI engines to Light cache.
1.5. Set the light cache mode to Progressive path tracing.
1.6. Optionally, you can turn on the Frame stamp to print the
render time on the image.1.7. Check the Enable built-in frame
buffer option in the V-Ray virtual frame buffer rollout. This is
not necessary, but allows you to safely zoom and pan through the
rendered image during the rendering process. Using the 3dsmax VFB
may cause 3dsmax to crash if you zoom/pan during rendering.
1.8. Render the scene. You should see the image being gradually
sampled, more noisy at first, but getting better as more samples
are added:
Step 2: Adjusting the noise levelThe image above is fairly
noisy, although it is computed quite quickly and can be used for
previews. However, for final renderings, we would like to reduce
the noise. This is done by adjusting the light cache Subdivs
parameter.3.1. Set the light cache Subdivs to 2000.3.2. Render.
Rendering now takes more time, as V-Ray computes more samples.
Since we increased the Subdivs twice, render time will
approximately quadruple:
3.3. If you want to reduce noise even further, increase the
Subdivs even more. For rendering stills, you can set this to a very
high value and wait for as long as you like before cancelling the
render and using the result. Here is a render with 20000 subdivs
which was cancelled after one hour:
Step 4: Adjusting the bias of the GI solutionFor the images
above, we used the default settings for the light cache (except for
the Subdivs parameter). The default settings use the light cache as
an aid during GI calculations. This helps to reduce noise in the
final image, at the cost of introducing bias to the GI solution.
This bias may show up as light leaks under thin walls or splotchy
secondary GI. In most cases however, the difference between a
biased and an unbiased solution is minimal.You can use the light
cache Sample size parameter to control bias. Larger values will use
larger light cache samples and will increase the bias. Smaller
values will decrease bias but may use more memory. A value of 0.0
will not use any caching at all and will produce an unbiased
solution. Here are three renderings with different values for the
Sample size and with the same Subdivs value (1000). There isn't
much of a difference in this simple scene, but in more complicated
situations, the noise reduction can be significant.
Sample size = 0.04
Sample size = 0.02
Sample size = 0.0 (unbiased solution)
Rendering with materials
Step 1: Rendering with materials1.1. Turn off the Override mtl
option from the Global switches rollout.1.2. For faster previews,
return the Subdivs for the light cache to 1000.1.3. Render:
At this point, you can adjust material settings etc, while
getting relatively fast feedback.Step 2: Better quality with
materials.Since the noise level is determined by the Subdivs
parameter, we only have to increase that. Individual Subdivs for
materials (f.e. glossy reflections/refractions) do not matter.2.1.
Increase the Subdivs parameter to 2000 and render. Rendering now
takes more time, but the noise is reduced:
By default, V-Ray does not compute reflective GI caustics, since
these tend to add noise to the image. Sometimes however, they are
important for the final result.2.2. Turn Reflective GI caustics on
from the Indirect illumination rollout.2.3. Render the image.
Reflective caustics can be seen on the green patch and the sphere,
as well as a general brightening of the scene. Notice that the
image is also noisier in places where there are caustics:
2.4. To reduce the noise in the image, we will need more Subdivs
for the light cache, for example, 4000. Since we increased the
value twice, render time will again approximately quadruple:
Note that you cannot obtain GI caustics from perfectly specular
surfaces with point light sources. Either the light source must be
an area source, or the material must be glossy, or both. You can
also use photon mapping to generate the caustics through the
settings in the Caustics rollout. This method is not as precise as
the GI caustics, but can handle point light sources with perfect
specular surfaces.Increasing the image size
The only thing to remember when changing the image size is that
larger images are noisier compared to smaller ones for the same
light cache Subdivs value. This is because the samples are
distributed over more pixels, and so each pixel gets fewer samples.
To compensate for this, you will need to increase the Subdivs
value. Increasing the resolution twice means that you will also
have to increase the Subdivs twice to get the same quality (and it
means that the render time will again quadruple). Here is the last
image rendered at 800x600 with 8000 Subdivs (click for the full
version):
Notes The image sampler type (Fixed, Adaptive DMC, Adaptive
subdivision) is ignored in this mode, since the path tracing
algorithm does pixel supersampling automatically. After the image
is complete, V-Ray will print the minimum and maximum paths that
were traced for the pixels in the image. The antialiasing filter
however, is taken into consideration. Note that sharpening filters
(Mitchell-Netravali, Catmull-Rom) may introduce noise and will
require more samples to produce a smooth image. Larger filters like
Blend may also take more time to converge. Turning the antialiasing
filter off produces the least noise. Subdivs parameters in
materials, textures, lights, camera settings etc. are ignored in
this mode. Noise and quality is controled entirely through the
light cache Subdivs parameter. The only parameters of the DMC
sampler that are taken into consideration are Adaptive amount and
Time-independent. Never set the Adaptive amount parameter to 0.0
when using path tracing, since this will bring the rendering to a
halt. At present, only the RGBA channel is generated by the path
tracing algorithm. Any additional GBuffer channels are ignored. The
light cache has no limitation on the number of diffuse light
bounces in the scene. The number of specular bounces (through
reflections/refractions) is controlled either per material, or
globally from the Global switches rollout. At present, the path
tracing mode does not work properly when rendering to fields. At
present, the path tracing mode does not work with matte
objects/materials. At present, V-Ray can only generate 2^32 unique
light paths internally. The light cache Subdivs spinner is limited
to 60,000, which gives 60,000^2 = 3,600,000,000 unique paths. Since
these are distributed across the entire image, for very large
images it may be impossible to get enough samples per pixel for a
smooth result. For example, a 2000x2000 image can be computed with
at most 900 paths per pixel - which may be inadequate for a smooth
result. In that case, using a traditional sampling method (brute
force GI) may prove a better solution.