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How to create a photomontage…

Have you ever wondered how to create a photomontage, completely from scratch?

Going from this…

Create a photomontage | Original photograph to house our montage

… to this

Create a photomontage | Our final photomontage with a CGI superimposed over a photograph

Well – we’ve got you covered. Here’s how it is done.

Firstly, what is a photomontage?

A photomontage is a mix of two different media. A computer generated image (CGI) is overlaid onto a photograph to show a new design superimposed into its existing surroundings.

Stitch a CGI onto a photograph to market property or win planning permission

Whilst traditional CGI allows us to model the surrounding environment; photomontages offer us the opportunity to view the real-life surroundings as captured through the lens of a camera, which is often required when trying to win planning permission.

What is the recipe for a successful photomontage?

In it’s purest sense, we can break down how to create a photomontage into four fundamental steps…

Create a photomontage is made by combining a photograph, sketchup model, CGI using v-ray, stitching them together in Photoshop


Step 1: The photograph.

The photograph that we are to use for the photomontage can be considered as our ‘base’. All subsequent work depends on the initial photograph that we would like to stitch our CGI onto.

High quality photographs make for high quality photomontages

As a result, we need to ensure that it ticks all of the boxes before we progress…

  • The industry standard for photographing Architectural forms dictates that all of the verticals must look vertical within the image – ensure that the camera is not tilted up or down!
  • Consider the lighting conditions, as this is something that we will aim to copy within our CGI. Clear blue skies or a flat, overcast day – the choice is completely up to you.
  • The resolution of the photograph is important. We want the highest quality possible – we like our photographs to be 5000 pixels along their longest edge.

In terms of the composition, we need to remember that we will be overlaying a CGI on top of our photograph, which means that we need to ensure that we leave space within the frame to do so!

To maximise the quality of our final product, ensure that we can save out our photographs in RAW format.


Step 2: The SketchUp model.

Create a photomontage | It is important to model as accurately as possible to ensure that the model overlays perfectly over the photograph

Now for the fun part… let’s get modeling using SketchUp!

We must now model the proposed design – we run over the basics of how to do this on our Access into SKP course, and we cover more advanced modelling techniques on our bespoke Top-Up courses or 3-Month Development Programs.

Once we have ourselves a detailed model, we need to roughly match the SketchUp camera angle to that of the photograph.

This is the perfect time to think ahead to our CGI and try to match the resolution to our photograph (remember to ensure that safe frame is ticked!)

Create a photomontage | We must adjust the resolution within V-Ray to match the photograph

A key part of this process is ensuring that we match the Field of View (FOV) – this is akin to ensuring that we make sure that we use the same lens within SketchUp that we did for the photograph in real life.

Within the metadata of our photo, it often tells us the focal length of the lens that captured the shot…

Using the metadata, we can determine the focal length of the lens used to take the photograph

Within SKP, we then head up to View and then choose Field of View…

Within SketchUp, we can adjust the field of view, by going to camera and then highlighting Field of View

Here we type in our FOV value in mm, followed by enter – note how the camera within SKP changes.

Focal length sketchup model

The next step is to reposition the camera to match the photo. We do this by adding our photo as a watermark within the Styles panel of the tray as shown.

Using Styles within SketchUp it is possible to add a watermark image overlaid over our SketchUp model

This image overlay acts as a guide as we adjust the camera so that our model sits perfectly within the photo! Hit ‘Add Scene’ to save this angle!

Using Styles within SketchUp it is possible to add a watermark image overlaid over our SketchUp model


Step 3: The CGI

We now have a SketchUp model which is aligned to our photograph – let’s prepare our CGI using V-Ray

The first step is to develop our materials within V-Ray so that they look realistic. If you are new to this, check out our blog on creating realistic textures.

How virtual textures are broken down within V-Ray for SketchUp

Matching the lighting in the CGI to the photograph is important, so we need to ask ourselves the question…

Are we going to use the V-Ray Sun or opt for a Dome light?

Our recommendation would be to use the V-Ray sun if your photo was taken on a sunny day.

Whilst interactive rendering, we can move the position of the sun manually as shown below to match the shadows seen in the photograph.

 

Adjust the sun position using V-Ray 5's Asset Editor for SketchUp

This technique allows for a great degree of control, enabling you to truly match the lighting conditions as you see fit!

If your photograph was taken on a day with no direct sunlight – we recommend using a dome light.

Typical examples of this would be for cloudy days, photos taken at dawn, dusk or even at night.

Check out our blog on dome lights which explains how we go about adding these into our scene.

A preview of a 3D scene, lit using a Dome Light. The HDRI image used is from PG-Skies.

Pay attention to try and find an HDRI that matches the lighting conditions in your photograph!

Final render

Before pushing the button on the final render, ensure that we tweak our exposure to roughly match that of the photograph (we can refine this later).

We must match the exposures between the CGI and the photograph

For more info on how to improve the quality of your lighting within your CGIs, check out our blog on the topic here.


Step 4: Marrying the CGI with the photograph

Now that we have the raw materials, let’s bring these into our image editing software – we highly recommend Adobe Photoshop.

Overlay the CGI on top of the photograph.

Add a vector mask, and begin removing sections of the CGI which we do not need

Masking within Adobe Photoshop is a crucial step when creating photomontages

It is possible to use other render elements to help with this masking process – we coach artists on this topic on our tailored Top-Up courses.

At this stage, we also look to match the tones of the materials within our CGI to those seen in the photograph.


Et voila!

Our final photomontage with a CGI superimposed over a photograph

We hope that you have enjoyed reading about our process to create the perfect photomontage, from start to finish!

Keep an eye out for next month’s blog on how to scatter realistic vegetation in our scenes!

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How do I create realistic textures?

Have you ever wondered how you can go from this…

Create Realistic Textures | A screenshot from SketchUp of a simple texture

…to this?

Create Realistic Textures | An advanced V-Ray material

Well, grab a brew and open up V-Ray – we want to show you how to create realistic textures using some common examples to help improve your texturing game within the V-Ray for SketchUp Pro workflow!

Basic Principles

Textures (see also; materials) are painted onto faces within your 3D modelling software, and these can be flat colours or image-based.

The process within SketchUp to import images to use as textures
The process within SketchUp to import images to use as textures

In our first example, we are going to begin developing a wood floor texture – and so we need to find an appropriate image to use here.

We recommend Poliigon or Extreme Textures if you are looking for high-resolution images to use as materials, whilst SketchUp Texture Club is another source with an extensive library.

In this example, we are importing Extreme Texture’s Antique Oak into SketchUp as a Texture, which will allow us to paint this onto a face.

The process within SketchUp to import images to use as textures
How to import images to use as textures within SketchUp

Now is a great time to check the scale – within the Materials panel of the tray; use the global size settings to ensure that our boards are scaled appropriately. To help me do this, I like to draw a guideline that equals the desired width of the board, so that I have something to reference.

Create Realistic Textures | Within SketchUp, we resize the texture globally using the material panel within the tray.
Using a guide line for reference, we resize the texture globally using the material panel within the tray.

Here we can see how important it is for our material to be seamless. There is a vast collection of seamless materials available from the sources mentioned above!

We now have a high-quality, seamless texture applied to our model which is the correct scale.

Why does this not look realistic yet?

Create Realistic Textures | A SketchUp texture

Building Blocks

Light.

What V-Ray allows us to do is to bounce light around our model and control how our materials interact with it.

Create Realistic Textures | How virtual textures are broken down within V-Ray for SketchUp
Virtual textures can be broken down into three maps.

As covered on our Access into V-Ray for SketchUp courses; most solid materials can be divided up into three mapsdiffuse, reflections and roughness.

The diffuse texture is what we see within our SKP model. This can be considered our ‘base’ texture and defines predominantly what the material looks like without lighting or roughness effects applied.

A diffuse map is often considered our base texture.
A diffuse map defines what our texture looks like. Texture map courtesy of Extreme Textures

If light bounces off an object and is not absorbed, then one sees a reflection. V-Ray has the ability to control the intensity and glossiness of reflections of materials within the scene by using reflection or specular (see also; spec) maps. For example, areas on a texture where one would see a glossy finish would show up as white on a spec map, whilst matt areas appear darker.

A specular map dictates where on the material we will see glossy or matte reflections
A specular map dictates where on the material we will see glossy or matte reflections. Texture map courtesy of Extreme Textures

Not all materials are as flat as a mirror; for this, we use a bump or normals map. Areas on a bump map that are darker are shown as depressions on the surface of the material when rendered, whilst the opposite occurs for lighter areas. Be careful with the intensity of bump or normal values – anything above 1 is normally not required.

A map that is used to simulate 3D depth to the texture.
A bump map is used to give the texture some 3D depth. Texture map courtesy of Extreme Textures
Adding Complexity

Hold on… how does glass work?

Refraction colour dictates how much light 'refracts' through a material.
Refraction colour dictates how much light ‘refracts’ through a material.

As we can see, the lighter we make the refraction colour, the more ‘glass-like’ our material becomes.

We can deduce that the setting to use that controls the transparent properties of glass is called refraction. Like with the reflection glossiness, we also have the opportunity to create frosted glass by adjusting the refraction glossiness value!

Refraction glossiness enables us to define shapes on the other side of the material.
Refraction glossiness enables us to define shapes on the other side of the material.

What about fabrics?

Depending on the qualities of the fabric in question, we would advise taking a look through the preset textures within V-Ray…

V-Ray offers plenty of preset fabric textures
V-Ray offers plenty of preset fabric textures

Once a similar fabric has been chosen, you can edit the colour and tones of the diffuse, by right-clicking on the bitmap slot within the Diffuse, and wrapping it in a Colour Correction. Here you will be able to modify the hue, saturation, brightness and contrast, to your liking.

Adjusting the colour of materials within V-Ray for SketchUp
Textures can be re-coloured by wrapping the diffuse in a Colour Correction adjustment.

Fabric textures now benefit from a new feature in V-Ray 5 for SketchUp where you can add a translucent layer for extra realism.

V-Ray 5 for SketchUp now offers the opportunity to add a coat to materials for added realism.
V-Ray 5 for SketchUp now offers the opportunity to add a coat to materials for added realism.

What if my texture seems to emit light?

One can add emissive layers to all materials within V-Ray as shown…

Emissive layers can be added to most materials.
Emissive layers can be added to most materials

You can also copy your Diffuse into your Emissive bitmap slot…

Diffuse maps can be added into the emissive texture slots
Diffuse maps can be added into the emissive texture slots

We cover how to create more realistic textures on our one-to-one, bespoke Development programs and Top-Up courses.

An example of high quality textures

Now that you know how to create realistic textures; Wrapping is a term we give to the application of a material to multiple faces within our model – much like the wrapping of a present with wrapping paper. We cover this in great detail on our Access into V-Ray for SketchUp courses.

We hope that you have enjoyed our texturing tips!

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Do you want to improve the lighting in your CGI?

Learning how to improve the lighting in your CGI is not rocket science, but there are techniques that we use. By understanding a few key lighting concepts I want to illuminate you and show you how to better your CGI, but before we do; let’s talk about why the sky is blue…

Let there be light.

Under intense and unimaginable pressure, hydrogen atoms are forced together in a huge release of electromagnetic energy, of which visible light makes up a small portion of this energy.

This is the beginning of the journey of a single photon from the centre of the burning ball of gas that we call our sun until it reaches our eyes.

Improve the Lighting in your CGI - The sun
Light is formed as a by-product of nuclear fusion

After its tumultuous birth, our photon then takes, on average, 6 minutes to leave the surface of the sun and fly across the vast, 150 million kilometers of hard vacuum until it reaches our atmosphere.

Improve the Lighting in your CGI - Golden hour at sea
Light then scatters through the atmosphere, turning the sky blue during the day and redder at dawn and dusk.

As our photon passes through the big air bubble that surrounds the earth, it bounces off and passes through nitrogen atoms which make up nearly 80% of our atmosphere.

Our photon is a package that contains all of the colours of the rainbow – it just so happens that light on the bluer end of this spectrum scatters through nitrogen most effectively… which is why the sky is blue.

Improve the Lighting in your CGI - an exterior CGI of a garden office made by Ventham Construction

On a physiological level, we have evolved not only to love light but to need it.

Light is the key component that enables us to see, gives us security, and stabilises our circadian rhythms which helps us to sleep deeper and more restoratively.

It improves our moods, decreases depression, and even increases cognitive performance such as reaction time and activation.

On a fundamental level, we have an innate and primal relationship with light that can be traced all the way back to the roots of our shared evolutionary tree.

“I sense Light as the giver of all presences, and material as spent Light. What is made by Light casts a shadow, and the shadow belongs to Light.” Louis Kahn, American Institute of Architects Gold-medal winning Architect

Improve the Lighting in your CGI - Louis Kahn's National Assembly in Dhaka, Bangladesh
Louis Kahn’s National Assembly in Dhaka, Bangladesh

Lighting in CGI.

Modern render engines and most real-time game engines calculate lighting in a way that aims to emulate reality.

By definition, rays are traced (note: ray-tracing), from light sources as they then travel through 3D space and bounce off or scatter through surfaces.

Ray tracing software determines the number of times that a ray can bounce off or through a surface – the bigger the number of bounces, the harder the PC has to work, but generally the more realistic the result. 

Improve the Lighting in your CGI - An interior CGI of The Priory in Tetbury

As experienced and industry-leading producers of CGIs, we wholeheartedly recommend V-Ray as our ray-tracing program of choice.

We use this in conjunction with SketchUp and have done so for nearly a decade now.

Improve the Lighting in your CGI - An exterior CGI of Paragraph 79, Kea House, Devon

Feel free to take a look at what our CGI production team is getting up to using this software combo!

These lights have to come from somewhere though, right?

Whether it is the sun, a light bulb, or a candle; it is the job of the 3D artist to add these light sources to the 3D space and program them to emit light realistically.

Improve the Lighting in your CGI - A preview of a 3D scene, lit using a Dome Light. The HDRI image used is from PG-Skies.
A rendered preview from PG-Skies.com of a scene lit by a dusk HDRI.

Check out our article on how to use Dome Lights to create night-time CGIs.

As humans, we respond differently to different environs and lighting plays a big part of that. Anything that we see has a direct link to the subconscious, and this is what CGI artists tap into when working with lighting in a visualisation.

How do I put this into practice?

If you have read this far, you already understand the power of lighting within a CGI.

We need a structured workflow to better enable us to generate realistic and emotive lighting setups within our work…

If you are relatively new to CGI production, I recommend our Access into V-Ray for SketchUp course!

Day two of this three-day course is dedicated purely to lighting.

We explore what light sources that we have available to us, and how we go about adding these into a scene.

We then explore the concept of ‘Three-Point Lighting’, which gives us a fail-safe method of programming the lights within our scenes to work together in a photorealistic way.

Improve the lighting within your CGI - Scout Farm with lights toggled on and off

If you already have a good foundation, and simply want to improve the lighting in your CGI, look into our Top-Up courses – the premise is simple:

  1. You pick what you would like to learn
  2. A bespoke, coaching session will be designed by us and then pitched to you before you commit to anything
  3. Once you are completely happy with the custom learning material on offer, this is when we schedule a coaching session – we book these out in half-day blocks, to ensure that you have ample time for study and information retention.
  4. The session is held online and is screen recorded – which means you can watch it back when practicing on your own.
  5. Upon completion of the course, we extend a helping hand by offering an after-care period of 30-days, whereby as you take this knowledge into professional practice; you can come to us with any questions that you may have.

All of our courses, now taught online, aim to give you the tools to consistently advance your visualisation skills and improve the lighting in your CGI.

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Dome lights: how do I use them to create a night time CGI?

You may not know it yet, but a dome light is the answer to creating ever-more realistic lighting setups within your CGIs…

Let’s break it down…

In a day-time scene, we have direct sunlight to illuminate our scenes. Direct light also scatters through the atmosphere and illuminates our environment.

A preview CGI from Peter Guthrie. Used to light a 3D scene using a HDRI within a dome light
HDRIs from PG-Skies.net. is a great way to illuminate your night scenes.

V-Ray considers both direct and indirect illumination as two separate light sources.

To create a night-time scene, we require a technique to remove direct sunlight, whilst being able to create a night-time environment.

To do this, we use something called a Dome Light

A flattened, spherical HDRI from Peter Guthrie. Used to light a 3D scene
A flattened, spherical HDRI from PG-Skies

A Dome light is a type of V-Ray light that surrounds our entire model, forcing light inwards. Images can be loaded into these light sources, which enables the user to simulate real-world environments by using panoramic HDR images. 

Learn more about the benefits of a Dome Light on our Access into V-Ray for SketchUp course

I like to think of a Dome Light as a giant snow globe – with our model in the centre. We can choose what the sky looks like by swapping in different panoramic images.

Now that we know what dome lights are; what does this mean for you?

How to insert Dome Lights into your 3D scenes within SketchUp

Select the highlighted tool to add a Dome light into your scene. Putting this into practice is straightforward. Pick out the Dome light tool from your V-Ray toolbar…

Loading a bitmap image into our Dome Light.
Click on the chequered box to import your HDRI…

Load in your HDRI…

Preview of a scene lit by Dome light using a spherical panoramic, HDRI image
Rotate to ensure that your shadows are pointing in the correct direction!

Hit render! Don’t forget to rotate your dome light to adjust the position of the sun

 

Over the years we have come across many different sources for dome lights…

We would like to recommend just two…

A preview of a 3D scene, lit using a Dome Light. The HDRI image used is from PG-Skies.
PG-Skies provide rendered previews so that you know what the sky will look like once rendered.

For variety, we highly recommend taking a look at Poliigon. Besides offering free assets; they operate a simple, subscription-type service where, depending on your package, you obtain different amounts of credits every month to spend on HDRIs, textures or models

If you are looking for top-quality HDRIs, look no further than Peter Guthrie’s shop – PG Skies. This in-depth collection of ultra high-quality HDRIs contains skies for all occasions. The handy preview renders show each of these in action, to make picking out your favourite that much easier!

 

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High quality 3D models of furniture… where to find them? 

A product CGI that demonstrates the sourcing of a high quality armchair model from Design Connected.
A Product CGI showing high-quality models downloaded from Design Connected.

We get asked this because SketchUp & V-Ray users like yourself are wise to the fact that adding better quality 3D models into your scenes adds realism to your work.

We are in complete agreement – from our experience; there is no other part of the visualisation process that boosts the quality of a CGI more than the usage of high-quality, realistic 3D models…

Check out our work here!

Finding the right source… now that’s another question entirely…

 

Our favourite source is a website called Design Connected.

A screenshot showing a high-quality 3D model of a bed from Design Connected.
The Kelly Bed, by Poliform. A Design Connected 3D Model.

We have no affiliation with these guys – but we rely heavily on their models. Without a doubt; they are the place to go for high-quality SketchUp models of furniture, lighting, and accessories.

For over 10 years, they have worked with premium brands to provide photorealistic 3D models of their products – so that SketchUp and V-Ray users like us can download and import these into our scenes!

All models are (or can be) made available in SketchUp format, and all textures are correctly applied to each model, meaning it is the closest thing to a plug-and-play technique that exists for our workflow for furnishings

 

Another source that we use is 3D Sky.

A website screenshot of 3D Sky showing the range of 3D models available to download
A screenshot of 3D Sky showing the range of 3D models available to download

Again, we have no affiliation with this website, however, we have really benefited from the vast 3D collection that they offer.

If models are not available on DesignConnected, we head over to 3DSky, safe in the knowledge that we will find something that we can use.

Rather than the standard SketchUp file-type (.skp) that we are used to; models from 3D Sky tend to be in a different format – a filetype called obj

In a nutshell, they store the geometry and textural information that makes up a 3D model. Different 3D modelling programs use different file types to save models – however, the .obj file type is the closest thing to an industry-standard in this regard.

Transmutr allows you to convert obj, fbx, 3ds, dae files into SketchUp (skp) files.
Convert various 3D formats into SketchUp files using Transmutr

To import .obj models, we use an extension called Transmutr. The easy-to-navigate interface allows you to convert these into .skp files – for you to then import into your scenes.

This process can be covered on our bespoke Top-Up Courses.

 

For its value, the 3D Warehouse is an invaluable resource

An image showing a screenshot of a 3d model search using the 3D Warehouse within SketchUp
The 3D Warehouse has been designed around you. Find free 3D models for SketchUp scenes here.

If you are working under a tighter budget, without the capacity to spend much on 3D models – there is no better source than the 3D Warehouse within SketchUp’s interface.

If you own or have owned, SketchUp Pro – there is a very good chance you know about this already.

Use the sliders on the left to control the quality of the models within your search parameters.

Take note… these models are not quality-checked before being uploaded to the warehouse – which means that you can end up with a real mixed bag in terms of quality.

To be safe, we always recommend saving the desired models into their own files, rather than importing straight into your scene – as this protects your master file from any latent errors that may be present within the imported models!

We run over how to make the best use of the 3D Warehouse on our Access into SketchUp online course.

 

Without over-complicating things…

A CGI demonstrating the quality of furniture 3D models sourced from websites such as design connected, 3d sky and the 3d warehouse
High-quality 3D models bring your CGIs to life. Invest time in sourcing the best quality 3D models available to you.

If you are looking for consistent, high-quality 3D models – we recommend Design Connected.

Variety, on the other hand, is a real strength of 3D Sky.

If you are looking for free models – 3D Warehouse is the source for you.

 

Still doesn’t answer your question?

Model it yourself!

Join us for our next 3-hour, Bitesize course where you can learn to Model with Photography – follow the link for dates!

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