Beyond Architectural Illustration

Tuesday, May 13, 2014

Right or Left Shadows?

Which of the above images seems to have the better shadows?

I ask because of the convergence of two bits of information today.

First, on the Freakonomics podcast there was a discussion on how your cultural background can affect your view of the world (e.g. pessimistic vs optimistic). Professor of Psychology, Boaz Keysar, stated that he was “much more likely to invest in the stock market when I do it in English. If I think about it in Hebrew, I’m much more conservative.” My own experience with dual language friends agrees with that; the language used brought out a slightly different character.

Second, I had lunch with an old friend who taught architectural drawing for 20 years. He said that he gave an assignment for a drawing exercise, and stipulated that the light should come from the left. Two Israeli women turned in projects with the light coming from the right. They explained that it simply looked better that way. And, after finding that the rest of the English speaking class preferred the left light, he realized that Hebrew is written right to left, exactly opposite to English.

Coincidence?

Well… yes and no.

In both examples the culture probably makes some difference, but I can’t imagine that the difference is overwhelming, or even consistent.

As with my teaching friend, the accepted light angle for rendering elevations at the Ecole des Beaux Art was always a 45 degree angle from the upper left toward the lower right. However, a perspective is a different animal. When I find a perspective in my books from the Beaux Art era (which isn’t often), the light angle is often from the left, but is nearly as often from the right, or simply indeterminate. The perspectivists who were trained at the turn of the last century took their lighting cues from building orientation and the needs of composition. Goodhue and Ferriss have already been covered in this blog, but are worth revisiting in this regard.

Out of curiosity I reviewed a quarter of the drawings I did over 30 years. Of the 120 drawings and paintings, I found that 50 involved light from the left, 35 used light from the right, and another 35 had either indeterminate light direction or were lit artificially.

This seems to leave the question up in the air, but if any reader has an anecdote relating to language, culture and lighting please leave a comment.

Wednesday, May 7, 2014

Perspective - One Point Perspective - Distortions & Complications

Distortion is the principal cause of sorrow in hand layouts. A simple mistake at the initial marking of horizon and vanishing points can cause havoc in the final product. The following examples apply to both the cube examples of the previous posts, and to any layout, whether by hand or computer. It is a mixed bag of tips, so forgive the lack of order.

When creating a simple perspective using one point and a diagonal vanishing point, don’t stray far from the central point. The three cubes on the right are about as far from the central vanishing point as they can be. The cubes on the left are too far, and show some (or a lot of) distortion. Generally I try to stay within a circle whose center is the one point vanishing point, and whose radius is half way to the diagonal vanishing point.

In hand layouts or computer rendering, the closer your eye is to the object the more it will be like a wide-angle lens (see the plan and perspective on the right above). Distortion will start to occur at the edges the closer you get. Moving your eye away from the object will create a telephoto effect, flattening object (see the plan and perspective in the center above). You may need to get closer or further to see what you need to see, but keep in mind that this changes the aspect of the project.

The diagram above shows the distortion in both an exterior and an interior perspective when the eye is too close to the object or space; the object looks too long, and the space looks too deep.

This plan and layout shows that the distortion of the main room is acceptable, but the smaller room on the left is noticeably wrong.

So much for distortion. The final illustrations involve complications in layout. They are more for fun, but are good to keep in mind as you think about perspectives.

Here I’m taking the previous view of a large and small space, and showing how to make the large space into an octagon by slicing off the corners. The diagonal vanishing points are not very widely spaced, and so distortion is showing up.

If you have a plan that is rectangular you can use a diagonal “cross” to transfer the orthogonal plan onto a perspective shape. The green lines set up the transfer by directly moving lines to the perspective. In addition the green lines mark both the plan and the perspective with a diagonal “X”. The orange lines transfer all other lines to the perspective. Again, I’m not suggesting that it is the way to create a “perspectivized” plan since the computer does it in no time. But, it is something that is worth keeping in mind as you use the computer.

The illustration above shows that the grid can be used for the most non-rectilinear plan imaginable.

The photos above illustrate the perspective nature of stairs, ramps and escalators. If oriented the same way, they all will recede to vanishing points above or below the building’s vanishing point that is on the horizon.

The diagram and photo above address reflections in water in a perspective. Since water is generally below the ground level of a building, you have to plot the water’s level, and then mirror the building’s reflection from that point. Again, you will easily do this in the computer, but knowing what is going on keeps mistakes from happening.

Finally, a trick that computers can’t emulate. When drawing a perspective of a very small space like an elevator cab, you will find that the ceiling and floor will always look distorted. The easy answer to this problem is to create a “sliding” vanishing point. Instead of having a single vanishing point, use one vanishing point for the left wall (shifted toward the right), and another vanishing point for the right wall (shifted toward the left). The result is an elevator cab where the paneling joints look correct, but the vanishing points are actually shifting up (near the ceiling), and down (near the floor).

NOTE: These posts are NOT meant to be a tutorial on one-point perspective. There are plenty of websites that do that. I want to illustrate some of the interesting examples, and point out the major problems and opportunities out there.

Perspective - One Point Perspective - Using a Diagonal Vanishing Point

Constructing a perspective of a free-form object, or a bunch of misaligned objects is trouble, and should be done in a computer with a CAD and rendering program. If however you have a design that is regular and rectilinear, there are simple rules that will get you there without a lot of work.

A tiled floor of equal sized squares creates a repeating pattern across the width and depth of a room.

But, it also creates a regular diagonal pattern which establishes vanishing points to the left and right of the centered one point vanishing point. If the grid consists of squares, then you have set up a diagonal system that can be used to establish any floor plan shape.

A grid of regular lines on an elevation can be used in the same way.

In the photo above the grid is not made up of squares, so a number of diagonal vanishing points are possible. If you know the relative distances of vertical and horizontal spacing you can set up a measurable grid. In any case such a diagonal set of perspective lines will give you a grid to hang your design on.

Oh, alright. A short bit of graphic instruction would help here…

Draw a square, and then draw a horizon line 2 or 3 “squares” above. Draw lines from each corner of the square to the horizon line immediately above it. Strike a diagonal (dotted white line) to a vanishing point a reasonable distance to the side of the horizon line (You can do this by eye; a post on distortion will follow). By drawing a horizontal line where the diagonal crosses the lines connecting the square to the horizon line above you establish the top of the cube (white with cross inside). Carry vertical lines (green) down to the lower lines going to the horizon and you establish the bottom of the cube (red with cross inside). This last step can be done or checked by striking a line to the diagonal vanishing point from the lower right corner of the original square.

Fill in the cube with solid white and you have a cube facing you in one point perspective. Simple, dull, boring and surprisingly useful.

While a circle drawn in the front elevation is a true circle, a circle on the top (which is receding in perspective) is an ellipse. The cross helps to place the ellipse which I use a template when drawing in the ancient mode.

It is quite easy to multiply the cubes in any direction. The diagonal vanishing point defines all subsequent cubes.

As said before, the front face of the cube (or any multiple thereof) is a measurable surface easily marked with an elevation drawing.

More importantly, any front face is equally measurable and ready for an elevation marking.

The cubes can be extended left, right, up or down. The only limitation is distortion.

But here is the fun part of the endless cube. By striking diagonals to the vanishing point from the centers of each side you create a… cube seen in two point perspective! Yes, you will have to adjust the height to get it right, but practice will educate your eye.

Drawing elevations on the faces of this new cube is a little messy, but again, with practice and a good eye you can reproduce a two point perspective without doing a complete layout.

We’ve dealt exclusively with cubes up until now. What about cylinders? Well, we have already marked circles on the sides of a cube, so it is simple to consider the circles as the top and bottom of a cylinder.

Fill in the form, and voila!

Shade and shadow are useful to make the cylinder believable, but that is for another time and another post.

Caveats, caveats, and excuses…

Knowing the relationship between one point and two point perspective is very useful when working on something simple, or sketching an idea. If you want to produce a serious perspective, or want to see what a form looks like from all angles, go immediately to your computer. My reason for writing these post on perspective layout is not to replace the computer, but to supplement your knowledge about what is happening in the computer. Too many architects and designers have never worked out a perspective layout, but have gone straight to the computer. In my experience a little hands on work is necessary to make the most of the computer programs available.

Yes, I’m an old fuddy-duddy.