Ground Elements

Church and Farm Building

Aligning the church provides the first example of the benefits associated with the shadows being painted onto the ground terrain.

Now this is laid flat in three-dimensional space, we can use the shadows as markers for positioning our geometry in depth.

Fig 1: shows how, in this case a Card can be aligned to the reference provided by the shadow.

Fig 1: Card (with Church texture applied) is positioned and rotated to align to the corresponding shaow on the ground projection

One consideration would be the type of geometry to use for the church. In this case a card will be adequate because the camera move has very little lateral movement or rotation that may expose any change of perspective in the front and side facades of the building.

Camera projection, using the hero (frame 200) was used to apply the texture to the geometry, with the same justifications as previously described.

Decisions around the geometry to use for the farm building and adjacent tractor were made using the same rationale as was the placement in Z space (Fig 2). Again the camera projection method was used to assign the texture.

Fig 2: The same approach is taken witht he farm building and tractor

The Road Fence

The low fence along the side of the road, adjacent to the farm (Fig 3) comprises of two separate texture images, one for the left side of the road and the other for the right side.

Fig 3: A low (picket style) fence runs parallel, along both sides of the drive leading to the farm.

The method of applying the image to geometry can be derived from previous analysis given that camera projection has proven entirely favourable for this camera move. However this element presents new challenges around the type of geometry to use and how to configure it. On the matte painting (Fig 4), we can see that it follows the contours of the ground and the sweeping curve of the road.

Fig 4: Undulations in the ground

However, because this section of the matte painting transcends the Z axis, a Card will not provide an accurate presentation and the graphical element as it will slide across the ground when viewed from the moving shot camera. Even if placed diagonally, it cannot adequately follow the contours and curvature in the 2D image.

One solution can be found in the use of a cylinder (Fig 5), in this case scaled to create an oval and then rotated on the Y axis and positioned to follow the curve of the left side of the road.

Fig 5: A cylinder primitive is manipulated to follow the curves in the driveway

This was then repeated (Fig 6) to create a similar surface to catch the right side of the fence.

Fig 6: The same approach is taken to create and position a second cylinder for the right side fence

Each texture is then projected onto the respective cylinder using a camera from the hero (frame 200) and can be seen locked to the ground terrain when viewed from the moving shot camera (Fig 7)

Fig 7: Frames from along the shot camera’s motion path show the integrity of the projection

Gate and Tree

An almost identical solution was used to apply the foreground gate element (Fig 8). Again, because this sits diagonally across the Z axis of the ground terrain, the post and ‘hinged’ side of the gate reside at different locations on the Z axis.

Fig 8: Shows the position and angle of the gate is diagonal relative to the ground terrain

Consequently, projecting this element onto a card facing the camera, would result in separation and sliding between the ground and the gate (Fig 9).

Fig 9: Premininary render with gate texture applied to card prior to alignment

However by setting the card diagonally, and using the shadows painted onto the ground during the painting process to align, a successful projection is achieved. Fig 10 shows the card rotated, utilising the shadows from the gate on the ground projection) as visual cues

Fig 10: Card with position and rotation transform applied

Figure 11 is a preliminary render showing this second iteration

Fig 11: Render showing the improved stabilitiy of the gate

The same approach could be used to align and position the tree and tyre swing that occupies the left foreground (Fig 12).

Fig 12: Shows an identical approach used for the tree element

Camera projection was used to apply the textures to the geometry in all cases.

Hay Bales, Rocks and Foliage

The shadows painted on to the ground during the matte painting process provide further depth cues for placing the card geometry for multiple elements that make up the scene (Fig 10).

Fig 10: Shows alignment of the hay bales that occupy the right mid-ground.

What is significant here is that because spheres were used to raise the ground terrain, especially on the right side of the shot and where most of these staging elements reside, then the shadows now occupy differing positions on the Y axis as well as the Z axis. This adds an additional consideration when placing the cards for projecting the hay bales insofar as they need to be transformed vertically as well as in depth to achieve correct alignment.

Identical considerations and approach applied to the rocks, foliage and sunflowers that occupy the right foreground and extreme foreground (Fig 11).

Fig 11 shows alignment of the rocks, foliage and sunflowers