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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 to Align CAD

Modelling from CAD within SketchUp – where do I start?

If you are modelling within SketchUp, you will need to know how to import and align CAD drawings. Whether your own or somebody else’s; well-aligned CAD drawings are the literal foundations upon which you build your SketchUp models.

Let us explore how to align CAD in the most efficient way possible. To clarify; the plan is for us to import CAD before tracing over it to create our 3D model. Let’s get started!

Importing…

When initially importing a CAD file (in .dwg format), it normally enters the SketchUp workspace as a completely flat group.

CAD imported into SketchUp
Next step; organisation

Organisation…

Something else that you will notice is that all of the CAD layers are visible as tags within SketchUp. We don’t need all of these so we can compress these tags down into one which we’ll rename CAD. I would now recommend creating a tag to be used for the massing of our 3D model.

GIF showing the layers brought in during a CAD import to SketchUp
When importing CAD into SKP, layers are preserved

We also need to ensure that each floor plan and elevation is grouped separately.

CAD plans and elevations are grouped seperately after being imported into SketchUp
Grouping geometry protects it from being warped when manipulating later.

Reposition…

Now that we have organised our drawing, let’s begin positioning the plans and elevations. Take the ground floor and move it over to the origin as shown (also remember to align right angles on the plan with the red and green axis as you can see here)

A ground floor CAD plan within SketchUp which has been moved to the origin for ease of use
Moving the GF Plan to the origin is a great way to ensure that you are modeling using the red and green guides (or axes)

The next step is to align the elevations around the ground floor plan. Pay special attention to things like window and door openings, because we use these features to resolve whether or not we need to flip our elevations.

Elevations are lined up with the corresponding plans
Move and rotate your elevations to ensure that they are aligned with your plans. Remember to cross-reference to ensure correct alignment!

We can now stand up our elevations by using the rotate tool. A tip from us is to use the direction buttons on your keyboard once the rotate tool is active, as this will better enable you to lock the orientation of your rotation!

Align CAD drawings by rotating elevations in SketchUp
It is best to use the rotate tool to ensure that all elevations are stood up in preparation for modelling later.

Now simply place your first-floor plan over the top of your ground floor plan and lift up to the correct height as shown on the elevations. Repeat this step for each additional floor.

And hey presto you have now successfully aligned your CAD drawings! 

Aligned CAD drawings imported into SketchUp from AutoCAD
Next step: start modeling!

For more information on how this is done in practice, check out our Access into SketchUp and Top-Up courses, taught online with the Archilime Academy!

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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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Brought to you by the Archilime Academy