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.