Introduction Photomontage visualisation is simply a technique of combining a photographic background with a computer model of a proposed development in order to provide an accessible visual prediction. We live in a world in which imagery predominates and the importance and accessibility of informative visual material should not be underestimated. However it must be ensured that photomontages are prepared, presented and used correctly.
Part 1 VISUALISATION OVERVIEW PREPARED AS RECOMMENDED BY L.I. (UK)
Proposed Everton Football Club Stadium at Kirkby
Part 2 VISUAL SIMULATIONS PERSPECTIVE OR PERCEPTION?
The eye and the camera Human vision is much more complex than a camera because we have the ability to sharply focus on an object using a very shallow depth of field which provides the brain with precise distance information. When we focus on near objects, more distant objects appear out of focus, and when we view more distant objects, near objects appear out of focus. This blur enables us to judge distance. When we view a landscape scene, we are hardly aware of any foreground objects, so a photograph which has everything in sharp focus from the immediate foreground to the far distance is therefore an unnatural depiction of what we actually see.
The eye and the camera Although the human eye is an optical camera, it is the other parts of the human visual system which enable us to operate in three-dimensional space. Because we have the ability to assess distance, we scale the size of an objects by size-constancy scaling. Put simply, we magnify the size of our retinal image according to its perceived distance in the real world. The image below on the left was taken with a 50mm lens and one can see that the two people are approximately the same height because it is obvious that the person on the left is standing further away than the person on the right. If one compares the size of the same two people standing side by side in the foreground in the image on the right, the furthest person now appears to be even smaller, yet these are their actual sizes projected onto the retina at the back of the eye. We know by experience that both these people are about the same height because our brain taken into account the distance between them based on the many familiar texture and depth cues within the image itself and enlarges the relative scale of the furthest person.
The eye and the camera Our perception of scale becomes more of a problem in a photograph of a landscape involving considerable distances, due to depth compression where everything is in sharp focus and may lack reliable scaling or perspective cues. If a transparency of the landscape involving some distant hills is created where the real distance cues are clearly visible, it will fit the real landscape when viewed with one eye. When a printed image is viewed at the same distance, the vertical scale of the more distance hills is compressed, making them appear to be further away than they are in reality. It is for this reason that foreground objects should be excluded from visualisations because they will appear disproportionately larger than the more distance structures.
The eye and the camera The best example of size-constancy scaling can be found in Alfred Wainwright s Pictorial Guides to the Lakeland Fells published during the 1950 s and the 1960 s. He had the remarkable ability to represent what we see. Using photographs as a reference for many of his sketches, he increased the vertical scale of the landscape as the distance increased. In fact he said that it is necessary only to remember that the ordinary camera tends to depress verticals and extend distance and correct for this imperfection.
Camera formats The digital age has brought about huge advances in photography. One of the greatest advantages is the fact that the camera information is recorded with each frame, so where images require verification, this can be easily established from the camera metadata, which can be read in a variety of different graphics software SLR cameras are more suited to professional work than small compact digital cameras. However not all SLR cameras come with a 36mm x 24mm sensor. To keep down production costs, many companies produce consumer SLR cameras with electronic sensors smaller than conventional 35mm film. Technically they are not 35mm cameras and require a multiplication or enlargement factor to give the 35mm equivalent. For example a 28mm wide-angle lens on a camera which has a conversion factor of 1.5X will give a 35mm equivalent of 42mm. Similarly, a 35mm lens will give an equivalent of 52.5mm. As can be seen in the image, the sensor just crops the image taken by a lens with a wider field of view. The photomontages should be based on a replicable, transparent and structured process, so that the accuracy of the representation can be verified, and trust established. Moreover the visualisations should be easily understood, and usable by members of the public and those with a non-technical background. Standardisation of camera format and sensor size is essential if the images are to meet these criteria and be verified for accuracy.
Focal length The focal length of any camera lens is the distance between the optical centre of the lens and the sensor at the back of the camera when the focus is set to infinity. The shorter the distance, the wider the field of view, which makes distant objects look further away, and the longer the distance, the narrower the field of view, making distant objects look nearer. Camera lenses with a focal length less than the 50mm normal lens are defined as wide-angle lenses and those with longer focal lengths are defined as telephoto lenses. Providing photographs share the same central axis, images of different focal lengths will fit into each other when adjusted in lens correction software. This is best illustrated in the image below, which shows the relative fields of view of different prime or fixed lenses.
Focal length In a landscape, the focal length has to be carefully considered, as it can have a considerable effect on our perception of the scale of more distant objects. The next three images show the difference in vertical scale using focal lengths of 24mm, 50mm and 75mm. A 50mm single frame image increases the vertical scale of the landscape but still underestimates our perception of distance. A 75mm single frame image increases the vertical scale of the landscape and is similar to what we actually see.
Focal length The following two photographs further help to understand the effect of different focal lengths on our perception of distance and scale. Against the same landscape background which contains an existing wind farm, the images were taken from two different camera locations so that the person in the foreground who is standing in exactly the same position appears the same size in both images. In the left-hand image taken with a 24mm wide-angle lens, the turbines in the landscape behind appear much further away and are barely visible compared to the turbines in the right-hand image which was taken with a 105mm telephoto lens.
The 50mm lens and the human eye The diagonal field of view of 46 degrees of the 50mm lens is similar to the field of view of the colour-sensitive cones which give us our high-resolution vision. Due to the above mentioned similarity, one would expect that a printed image taken with a 50mm lens would be a fair representation of what we see within our area of detailed vision. However this is not the case; a 50mm photograph will always under-represent the scale of more distant objects, and the greater the distance, the greater the problem. The ideal focal length for representing a landscape In 2012, the University of Sterling conducted a study entitled The effect of focal length on the perception of scale and depth in landscape photographs implication for visualisation standards for wind energy developments. The main conclusions were as follows: The results suggest that images produced at a focal length of between 70mm and 80mm generally provide the most realistic representations of landscape scale and depth at least for the type of views considered during this study. The use of a single frame image produced at a 75mm focal length is therefore considered to be broadly appropriate for wind farm visualisation and that most likely to be acceptable to the largest proportion of the public. The prescription of a single focal length standard also has the advantage of simplicity and clarity for applicants. The use of alternative images produced at focal lengths shorter or longer than 75mm might be appropriate in very specific circumstances depending on the landscape context under consideration.
Part 3 IMAGES OTHER CONSIDERATIONS
Creating panoramas When photographs are overlapped horizontally to form a wider panoramic image, they are seamlessly joined together by stitching software. This can be created in two different ways; planar or rectilinear projection which creates an image which should be viewed flat, and cylindrical projection where the image should be viewed in a curve equal to the horizontal field of view of the panoramic image. Both types of projection can be created almost at the touch of a button in a stitching software, providing the images are made up of technically correct single frame images. Professional stitching software bases its calculations on the image metadata embedded within the original photographs themselves, so very accurate results can be achieved. If the panoramas are to be presented as printed images to be viewed flat in an environmental statement, only planar projection should be used, because it maintains an accurate landscape profile. Cylindrical projection can only be correctly viewed in a single frame viewer on a monitor or projection screen. Scanning the image horizontally through a viewer has a similar effect to turning one s head to scan the wider landscape as one would do in reality. Because the curved image is viewed flat in an environmental statement, serious inaccuracies occur.
Viewing images People tend to view photographs from a distance about equal to the diagonal of the page. A small-size A5 print will be held quite close to the eyes at a distance where one can see the image in clear focus, whereas a much larger A3 print will generally be held at a more comfortable arm s length The observation and recommendation by the University of Newcastle Report (2002) that what is comfortable for the viewer should dictate the technical detail and not vice versa was a very important point. Therefore the imposition of a geometrically exact viewing distance which can only be applied with one eye at an unnaturally close distance is therefore alien to most people, who naturally view a picture at a distance relative to its size with both eyes. The image on the next page shows an existing panorama, a wireline diagram and the proposed panorama all presented on an A3 size sheet. The images were taken with a 50mm full frame camera and the panorama stitched in a cylindrical format. The technical notes at the bottom of the page state the following: The angle of view is approximately 90 degrees. An interpretation of monocular perspective could be obtained by viewing from a distance of 250mm curved through 90 degrees. These photomontages were constructed according to the recommendations of the UK Landscape Institute Advice Note 01/09. The problem with this image is not the correctness of the camera matching or the construction of the photomontage but lies on the perception of the scale of the wind turbines. In fact this is a problem with most images presented in A3 environmental statements which require a viewing distance of anything up to 200-250mm shorter than our natural viewing distance relative to the page size. Therefore although the 50mm image should be viewed at a distance of 250mm (5 times enlargement multiplied by the focal length), this image ends up being viewed at a comfortable arm length, introducing the subtle but powerful underrepresentation of the visual effect identified by Professor Benson (University of Newcastle) in 2002.
Viewing images People tend to view photographs from a distance about equal to the diagonal of the page. A small-size A5 print will be held quite close to the eyes at a distance where one can see the image in clear focus, whereas a much larger A3 print will generally be held at a more comfortable arm s length The observation and recommendation by the University of Newcastle Report (2002) that what is comfortable for the viewer should dictate the technical detail and not vice versa was a very important point. Therefore the imposition of a geometrically exact viewing distance which can only be applied with one eye at an unnaturally close distance is therefore alien to most people, who naturally view a picture at a distance relative to its size with both eyes.
Part 4 ZTV / ZVI ZONE OF THEORETICAL VISIBILITY MAPS
Part 5 AVAILABILITY OF DATA MEPA S DATASET
LIDAR DATA
DTM & DSM
ORTHOPHOTOS
Part 6 PHOTOMONTAGES PRESENTATION & VIEWING IN THE UK
Photomontages as recommended by the Highland Council 2013
Photomontages as recommended by the Highland Council 2013
Photomontages as recommended by the Highland Council 2013
Photomontages as recommended by the Highland Council 2013
Part 7 VISUAL SIMULATIONS THE WAY FORWARD
What is the purpose of this document? The main aim of these guidelines is to formalise the way visualisations which shall form part of planning applications are prepared, presented & used. This will ensure that the visualisations: Are clearly and easily understood Are accessible to the public and Could be relied upon by all those involved in the planning process to inform their judgement. Preparation of visualisations The preparation of visualisations involves a number of processes, namely: Understanding the scale and context of the proposed development Establishing the location and the number of viewpoints Using the correct photographic equipment, data and software Ensuring that the correct technical requirements are adhered to when constructing photomontages Presentation of visualisations A summary of viewpoints shall be presented on a single drawing. Moreover each viewpoint shall also be presented individually on a separate drawing. Visualisations should be capable of being reproduced and printed such that all parties involved can clearly understand the scale and nature of the proposed intervention Visualisations need to be prepared and presented in a way to allow the verification of the images. This is possible by checking the original image data and a template to check that the image dimensions are correct Depending on the type of application being assessed, the applicant will be requested to submit either a combination of panoramic photomontages and single frame photomontages or else only single frame photomontages. Interpreting visualisations A photomontages which shall be viewed as a printed image shall clearly show technical information and viewing instructions
Part 7A VISUAL SIMULATIONS EXECUTIVE SUMMARY
All applications which require an EPS and EIS shall conform to the following: Item Contents Maps & Viewpoints All specified viewpoints visualised ZTV map Site and Viewpoint Location map Individual Viewpoint Location maps Summary of baseline images from each viewpoint Baseline photograph from each viewpoint Photomontages Baseline panoramas and wirelines (VFOV: 27 o HFOV: 65.5 o ) Year 0 photomontage panoramas (VFOV: 27 o HFOV: 65.5 o ) Year 10 photomontage panoramas (VFOV: 27 o HFOV: 65.5 o ) Single frame baseline images Year 0 single frame photomontages Year 10 single frame photomontages Methodology Statement Name and details of GIS software used for the ZTV Type and date of dataset used for the ZTV Original cell size of DTM Whether DTM has been downsampled or thinned Whether the ZTV analysis was based on bare-earth information Viewer height of ZTV analysis Whether earth curvature has been included in the ZTV analysis Type and make of camera Lens type: 50mm fixed lens Lens type: 24mm fixed lens Sensor size: 36mm wide by 24mm high Orientation of photograph: Landscape only for 75mm images Camera height: 1.5m Photographs taken with tripod Photograph of tripod Avoidance of foreground objects Weather conditions on site Photomontage preparation method statement Survey of viewpoints and reference points List of drawings used for 3d modelling of proposed development Planar projections for panoramas Correct viewing instructions, technical data on images
All applications which do not qualify for an EPS or an EIS but for which a visualisation study will be requested shall conform to the requirements set out in this document. However a proportionate approach depending on the size and context of the proposed development shall be made with respect to: Whether a Zone of Theoretical Visibility (ZTV) map is required, The number of viewpoints, The level of detail (LOD) of the 3D model of the proposed intervention, and Whether single frame images only as opposed to panoramas and single frame images will suffice. All images for all applications shall be presented on A3 pages in order to ensure that these are more accessible to a wider audience. Due to an increase of major projects in certain areas, MEPA may request the study of cumulative visual impacts. These types of studies shall be undertaken when an EPS or EIS is being requested. For projects which require an EPS or an EIS, a set of photographs of the completed project taken from the same viewpoint locations and under the same photographic conditions shall be submitted together with the compliance certificate to MEPA.
Part 7B PREPARATION OF VISUALISATIONS
The preparation of visualisations involves a number of processes, namely: Understanding the scale and context of the proposed development Establishing the location and the number of viewpoints Using the correct photographic equipment, data and software Ensuring that the correct technical requirements are adhered to when constructing photomontages The ZTV based on the building surface. The legend shows the vertical subtended angle from a grid of receptors
Part 7C PRESENTATION OF VISUALISATIONS
Bibliography New Zealand Institute of Landscape Architects, 2010. Best Practice Guide Visual Simulations BPG 10.2. www.nzila.co.nz/media/53263/vissim_bpg102_lowfinal.pdf Landscape Institute, 2009. Landscape Advice Note 01/09 Use of Photography and Photomontage in Landscape and Visual Assessment. www.landscapeinstitute.org Landscape Institute, 2011. Landscape Advice Note 01/11 Photography and Photomontage in Landscape and Visual Impact Assessment. www.landscapeinstitute.org The Highland Council, 2013. Visualisation Standards for Wind Energy Developments. www.highland.gov.uk/downloads/file/12880/visualisation_standards_for_wind_energy_developments Scottish Natural Heritage, 2014. Visual Representation of Wind Farms. http://www.snh.gov.uk/planning-anddevelopment/renewable-energy/visual-representation/ Kraft, R.N. and Green, J.S., 1989. Distance perception as a function of photographic area of view. Perception and Psychophysics, Issue 45(4) University of Stirling, 2012. The Effect of Focal Length on Perception of Scale and Depth in Landscape Photographs. www.highland.gov.uk/download/downloads/id/1024/university_of_stirling_study_of_visualisation_standards Alan Macdonald, 2012. Windfarm Visualisation Perspective or Perception? Whittles Publishing
END OF PRESENTATION