Tutorial SketchUp + Kerkythea


Bueno... en el curro me han pedido que escriba una guía de uso de la combinación SketchUp + Kerkythea, y me ha parecido que a lo mejor a alguien le puede interesar. Está en inglés, ya que está destinada a interns de diferentes nacionalidades (gracias a Dios no me lo han pedido en Deutsch), pero yo creo que se entiende bastante bien. De todas formas, si hay alguna duda concreta, no tengo ningún problema en compartir.

@jano, a lo mejor te interesa imprimirlo y que se lo lean tus compis ;) (primero revisa que la forma de trabajo sea la misma :rolleyes:)

Para animar a la gente a usarlo, cuelgo algunas imágenes hechas por mí en 3 meses manejando ambos programas, no los había tocado antes, y obviamente no sólo me he dedicado a esto, quiero decir que la curva de aprendizaje es muy alta. Warning, algunas tienen PS o Gimp después.


SketchUp + Kerkythea

modelling – rendering checklist


Before start, check the units to be set to meters.

If importing drawings from VectorWorks, make sure you export them at 1:1 scale, so they will have the correct size.

Always use the same position for the drawing, so you can import more files from VW, for example, or export different parts of the model to Kerkythea within the same position.

Use components if you are going to place the same geometry two o more times in the model. It can be from a simple box to the most complicated sculpture, it doesn´t matter. This will keep the use of memory in low levels.

Use groups to make objects independent, so they don´t “glue” to others.

Always check that you don´t see blue faces. All your normal must be coming out, so white faces.

Use layers to separate parts of the drawing. Walls, windows, furniture... or floor 1, floor 2...

Think in the materials that you are going to use in advance. For example, there are glass materials in KT that work better with boxes entities (two faces with the normals facing outside), others with just planes; you can simulate a fence with a clipping map in a material so you only have to create a plane, or if it has to be too detailed maybe not...

You are only going to render faces, so forget about the lines (a.e. don´t make a handrail with a line, but with a cylinder), and do not get too crazy about intersections, it´s only useful for SU views.

Apply materials to the model thinking that each material in Kerkythea will be an entity, and it´s much easier to change the position or size of the materials in SketchUp. So if you need the same stone tiles, with different directions, then apply it and “right click...texture” to set the correct size, rotation and position in each face. In this way, when exporting to render you will only have one material to take care about, and it will be in the right position.

As far as possible, use the bitmaps of the Kerkythea materials for the SketchUp materials. The UV maps is what we need to keep equal, but if we change the bitmap it then the “tiling” will be different. You can import these materials (well, not the material but just the bitmap since SU does not support other aspects) in “plugins...import kerkythea materials”.

For materials without bitmap (plastics, metals...) just apply a convenient color so you can identify it quickly.

For glasses or translucent materials, the name must be “TG_xxxxx”, to Kerkythea can understand that that´s a glass.

If you need to place artificial lights, there are two ways: emitting surfaces or light entities.

Emitting surfaces work fine, but you have to keep the number of faces as low as possible. Just create the geometry (a plane, or a hemisphere with few polygons), and apply a different material which will be an emitter later (remember, if you want different emitting intensities, you need different materials).

Light entities are “fake” constructions to simulate sources of light. In Kerkythea, you can use :

  • projector light, for sun.
  • IES light, only for the use of tabulated parameters of real light emitters (supplied by light companies, such as ERCO or LAMP)

  • omni light, spheres emitting light through all the surface.
  • spot lights, emitting in one direction through a cone.
The last two are quite useful for give some illumination to dark areas of the model, usually parts that we don´t have work on it enough, if we turn off the shadows. They can be used as light sources too, like lamps, but the emitting surfaces spread a more realistic solution.

Except for the sun(which is already in), you can insert those lights in SketchUp in “Window...Components”, and open the SU2KT light fixtures folder (you need to have them installed in the computer). It is better to place them in SU, and then adjust the intensity, color, etc. In Kerkythea.

Use the sun in SU as you want, you can export the same position to Kerkythea or just place a different location.

Each scene in SU will be exported as a camera in Kerkythea. Avoid using the zoom, use always different field of views, as it gives a correct physical description. Parallel perspectives are also supported, but you will probably have to zoom a bit in KT to match the correct distance.

If you hide layers on any scene and want them in the renderer, just make the exportation since a view with layers on.

Before exporting, go to “Window...Model Info...Statistics” and click on purge unused and fix problems.

To export, go to “Plugins...Kerkythea Exporter...Export model”. If you have any entity selected it will only export that one, so unselect all:

  • Geometry: yes
  • Lights: yes
  • Clay: no (this won´t export the materials, only glasses and white surfaces”
  • Photomatched: no (except if you are using the “Match Photo” tool in SU)
  • Default Uvs: no (overall if you have modified the position, or size, or rotation of a map)
  • Instanced: depends...

The use of instances in KT decrease the amount of memory needed, so it´s better. On the other hand, each component will be visible as a different material in the program, so if you have to make changes you will have to apply to all of them. So if you are sure about the materials, use instances, if you are going to change them, then no.

Remember that you can use several plugins for SketchUP totally free, that you will find on the web quite easily. Some of them can make your life easier, like joint push pull, or cylindrical UVs, etc.



After saving a .xml file of your model, you can open it in Kerkythea; right after open it, you can see the same view that you were looking at in SU.

In the left hand side is placed the scene tree view. This is a list of all the materials (the geometry), lights and cameras.

You can insert more geometry, lights or cameras: go to “Insert...” and choose the right one. The new camera will be placed in the actual view position, while the rest will start from 0,0,0.

To swith between wireframe and solid rendering, click “V”. If you are using the selector tool, to switch between move, rotate and scale click “G”.

To orbit around the model, always select some geometry, so it will rotate the view around it. If not, you will rotate around the axis origin.

To modify a camera, right click over its name, and click “Edit camera”. You can adjust here the parameters. The focal length specifies the angle of the objective. Wider angle (less number), more things you will see on the picture, but bigger distortion.

Use the pinhole f-number, unless you want some depth of field in the render (it is better to add it later in PS). The same for focus distance and lens samples.

You can change the projection type, to planar, cylindrical, spherical... Diaphragm and blades are used to affect to the distortion of the lights when looking at them directly.
Always click ok after doing changes or they won´t be saved.

In the same menu, you can edit the lights:

  • Enabled: you will see the light, but it won´t emit light.
  • Shadow: is useful to turn it off for ambient light (omnis used for bright some parts...)
  • Soft shadow: more realistic shadows, need more time to compute.
  • Negative light: only if you are rendering a night scene.
  • Global photons: yes
  • Caustic photons: doesn´t matter, since we do not use caustics (and you will always have the whole internet to learn about it)
  • Shadow color: black by default, only change them if your shadows are becoming too strong
  • Radius: 0,1 - 0,5(masterplan view, 0,5; detailed interior, 0,15)
  • Multiplier: it sets the strength of the light. It is good to combine this value with the sky intensity.
  • Radiance: specifies the color of the light, for sun a light yellow-orange.
  • Attenuation: none for sunlights, it sets the decrease of light intensity. When you select the light, the sphere or cone that you see is the limit of it.

And global settings:

  • Volume lighting: some materials, like the ones with complex subsurface scattering need to have it on. Check if you are using it.
  • Ambient light: black by default, used to “tint” a bit the scene.
  • Index of refraction, transfer recursion depth and scatter density are related to the way that atmosphere particles affect the light. Global fog is used to add some fog to the scene, which is better to add in PS.

To change the materials (a.e. Pink material in SU that we want it to be steel), right click on the name of the material, apply material, and select it from the library. You can download libraries from the web and install them or create your own.

You can do this also in “Settings...Materials”m where you can see all of your materials in the scene. To refresh the view of the thumbnails, right click over them and “Rebuild selected”. If you open a library on the right, you can replace one material in the scene selecting it, and click right on the material you want in the library, and then “Apply to left pane”.

By clicking twice you access to the material editor. As common rule, is always better to use an existing material and replace the bitmaps or colors, so we can use the same other settings. So if we want a wood, we have to apply a wood material from one of the existing, and then replace the diffuse and bump map.

There are different shaders to build a material:

  • Matte/Phong, mostly all of the materials can be represented with this shader, including emitting surfaces.
  • Thin glass, to create quick glasses by just giving a color of transmittance and an index of refraction.
  • Dielectric/glass, with all the parameters to simulate physically correct translucent objects.
  • Anisotropic, for surfaces with different properties in each direction (x and y). Leather, some liquids, tree leaves...)
  • Lafortune, to represent coatings, like the metal painting of a a car.
  • Layered material, where you can add some of the previous to create complex materials. You can adjust the blend between the layers using the “weights”, with procedurals, maps or colors.

To set up an emitter material, just choose Matte/phong, and click on “Radiance” under “Self Luminance”, and add the color of the light (or a map). Set the power, units, efficiency...
In every channel of the materials (diffuse, specular, radiance, bump...) it is possible to use many maps, or procedurals, or colors. So you can change easily the color of a brick by adding some red color in the diffuse channel. Take care of the weights, the total addition should be 1.

Procedurals are algorithms that represent a specific behavior, like fresnel, perlin noise, tiles... They are very useful and is very convenient to learn how to use them.

If we do not have a bump map for our material and we need it, we can create one from the diffuse bitmap. In Photoshop, apply the “Curves” and create a big contrast. Then turn it into grayscale image, knowing that the black means “back” and white “front”. You can add some detail or modify it as you need.

In KT material editor, you can add the bump map, and set the strength. If is not working properly, maybe you should check the bitmap options, “inverted”.

The clip mapping is used to “cut” the material with a black and white image that you apply: only white areas will be visible.

It is highly recommend to add some bevel mapping, at 45°, to make an effect of round edges, so they do not look so sharp. Depending on the size of the model, a value of 1 or 2 could be enough.

The fog settings are used in scenes with fog, and as we have said before, it is much better to add it in PS (better control of the effect).

The model flags are quite clear in their meanings, just remember that enabled and visible are different, so you can create light emitters that actually emit light or blocks casting shadoes, but without seeing them.

The reflectance, transmittance or attenuation menus work like in most render engines, with colors or maps to set the transparency, translucency or shineness of the material, index of refractions, or the math function used for the specular attenuation (None, Cosine or Fresnel).


After edit all your materials, save all of them in a new library (on “Settings...Materials”, select them and right click, “Send to library...”, and then save it), with the name of the project. This is helpful if we have to re-import some geometry, to look for a specific material after a while or to keep working on the scene in a different computer).

If one of the materials looks weird on the visor, maybe we have to work on the UV map. Select it, and “Tools...Bitmap coordinates). You can select the way the material should be projected over the geometry, following the UV map, box, cylinder or sphere. You can also adjust the scale, offset and rotation.

Once we have set our cameras, lights and materials, it is nearly done. To set the environment, we have several options, all of them in “Settings...Sun and Sky”. In the first window we can specify the date if we didn´t do it in SU (or if we need a different one).

In the next menu, we can select the type of sky:

  • Background color, background tiled image and background fit image, will not emit light, we need a light in the scene.
  • Sky color or Sky probe, to set a color or an image emitting light to our scene.
  • Hemispherical sky, Spherical sky, useful with HDRI images.
  • Physical Sky, simulates the sky depending on the date and location you set before.

All of them can modify the intensity and turbidity, to give more light form the background or to make it “dirtier”.

You can also just use a predefined global environment(many available on the web), by “Insert...Globals”. They are usually created with HDRI images.

If we are using an image as background and we want it to rotate to see another part, besides you can select the global and rotate it i recommend change the compass, so the sun will change also.
Time to render! In Kerkythea we have several predefined sets so we do not really need to be messing around with the settings. In general:

  • Biased render, with ray tracing+photon mapping+final gathering+antialiasing (not always all of them). It is fast for tests at low settings, so use the presets 03, 04 or 06 to check the lights, the materials, exposure...
  • Unbiased render, with different algorithms, such as Path Tracing, Metropolis or Diffuse interreflection. They give the best results, and despite each one is better for specific conditions, i recommend presets 17 or 19. In addition, if you use emitting surfaces, those methods are much faster. They need a lot of time (consider that a good quality can be at the pass no. 35 – 50, which usually means hours).
There are other presets that are often useful:

  • Mask render, is like the alpha channel, it will paint white the geometry that you select, so you can use it in PS later to cut it out, like windows on an interior view.
  • Clay render, it turns your bitmaps and colors into white, so it is recommended to study shadows.
  • Depth render, gives you the depth of the view, so you can add some distortion blur later in PS.
  • Lrs...specific aspects of the materials, useful to increase the intensity of the lights or add more reflections, etc.
  • Ambient Occlusion, creates a generic shadow that enhances the corners, so the volumes become clear. For fast volume renders, use it with the sun disabled (not only hide) and a white sky color.

Other settings in the start render menu are threads, the number of threads of your computer that you want to use; network, depending on the network settings of the office; render in background, to let the user keep working on the computer without lost of fluidity (requires more time), and resolution.

To set the resolution we need to know the final size of the printed image. The computer works at 72 dpi, and usually for color printing we are asked for 300 dpi, even 600. In my opinion, with 200 dpi is far enough for any render, but... So we just calculate the pixels we need:

  • for an A4, at 300 dpi.: (29,7 cm/2,54)x300= 3507; (24cm/2,54)x300=2835; so 3507x2835
  • for an A3, at 150 dpi.: (42 cm/2,54)x150=2480; (29,7cm/2,54)x150=1754; so 2480x1754

To create a sequence of cameras or an animation, select the cameras you want to use, and then “Tools...Walktrough Animation”. For a sequence, set the duration to 1 second, the rate to the number of cameras, and the speed at zero. The “bad” part is that we can not specify different resolutions for each camera, or different render method.

The Instances brush is a nice tool to create grass, forest... or anything that you can think



Muchísimas gracias EXIT! Menudo curro que te has pegado :) Voy a echarle un ojo, que estas cosas está siempre bien tenerlas ;)


Grande, eres muy grande, EXIT!!!
Muchas gracias por colgarlo!!!

Una preguntica: ¿Kerkythea es gratuito? :confused:
Porque yo usé en tiempos sketch up+artlantis que es sencillísimo; pero Artlantis es de pago y querría probar nuevas cosas aprovechando el tirón de los "pogramas" gratixxx.

Un saludo! :)


Wow!!! Es un trabajo espectacular, en serio! :) Una pregunta: El Sketch up que se necesita para poder utilizar el Kerythea debe ser el de pago??


Jo, estoy buscando por internet para potenciar el contraste luz/sombra en kerkythea, y me encuentro esto ahora :) Gracias por el trabajo, exit... :)

Por cierto, sigo buscando cómo solucionar lo del contraste, a ver qué encuentro.