Rob Adams a Painter's Blog painter's progress

July 25, 2018

Sun Cast Shadows

Filed under: Drawing,How to do,Perspective,Uncategorized — Tags: , , — Rob Adams @ 6:04 pm

This is a brief tutorial on the construction of shadows as they are cast from the sun. We all know how descriptive they are, the long shadow of a fence over a path, a telegraph pole over a road, spreading from the feet of people on the beach at the end of the day. Shadows in a painting tell the viewer more about the day than you might expect. A shadow crossing a road shows how high the verges are relative to the road, describing the shape of the land. We instinctively understand from shadows what time of day it is, even which season. If you understand how they are cast and how to get them correct you have quite a powerful tool in your painting box.

Here I want to deal briefly with the simplest of possible cases, but hopefully give you an idea of how the same methods might be used in more complex scenarios.

So our first example, a set of posts.

shadows, tutorial

The time is 1pm. See the changing angle of the shadows and how although in reality all the shadows are the same length in our perspective view they vary in thickness and length. Let’s move the clock on an hour.

 

Shadows, tutorial

Here we are at 2pm the sun is at it’s highest due to the magic of daylight saving summer time! People often imagine the shadows are splayed because the rays radiating from the sun, but this is not the case. The sun is 93million miles away so if we looked straight down from the top all the shadows would be the same length and parallel. So the effect of the shadows splaying is due to perspective and nothing else. On one more hour.

shadows

No surprises here at 3pm the shadows have swung round and lengthened again as the sun has dropped nearer the horizon. So let us look at 2pm again and look at how things got to where they are.

shadows, tutorial

A very tall skinny illustration since we have to get the sun in!

First the Red lines. If we drop a line vertically down to horizon we find it hits exactly at the point where the shadows converge at the horizon IE, the shadow’s Vanishing Point. If we had the shadows and no sun (as we might have in a reference photo) we could extend the shadow lines to the horizon and then project that point vertically up. We know the sun must be on that line… but where?

For that we need the Green lines. If we start from the sun again and fire a ray from the sun so that it skims the middle of the very top of the pole. Where that ray hits the ground marks the length of the shadow. Once again if we work backwards we can draw a line from the end of our shadow and through the middle of the top of the pole, extending it on we find it crosses our red line at exactly the sun’s position.

Shadow, tutorial

Here is a simplified version with  just a plank. As you see it also shows how the shadow gets wider in perspective as it gets nearer. Now a more complex example, a sculptor’s table with hammers upon it. First a quick video.

You can drag the slider and watch the shadows in motion. Once again here are a few times of day.

shadow, tutorial

Here is our table at 10am.

shadow, tutorial

…and at 12pm. Compare the two images and see how the various parts have moved. On 2 more hours.

shadow tutorial

Finally here we are at 2pm with the sun at its highest. Time for another tall skinny illustration with coloured lines!

shadow tutorial

Starting with the red lines. A line from one corner of the tabletop shadow then taken through the real corner and extended up crosses the same line drawn from another corner (any corner will do) at the point where the sun is. The blue lines show the splay of the shadow of the table legs and obey exactly the same rules as the posts did. The two vanishing points of the sides of the table top shadow are exactly the same as the vanishing points for the table top itself.

Similar rules govern how shadows from artificial lights are placed. If the ground is sloping or the posts at an angle then obviously the geometry gets more challenging. A more complex description is on the excellent Handprint site.

July 19, 2018

The Il de Re

Well off to France with a bus load of other painters. You try not to imagine how it will be or the paintings you might paint, but it is hard not to. I have been to St Martin on the Il de Re several times before so I knew what the possibilities were. My first visit was an oil disaster finding me able to catch the mood and light in watercolour but failing utterly to do so with the oils. My second visit a few years later was an improvement so I hoped to manage a few decent pictures this time. Also this time I took my folding bike so I could get further afield. What order… I suppose as I did them.

First up St Malo.

St Malo, France, pen and ink, drawing

We usually begin our trip in St Malo. We arrive quite early slightly ferry lagged before the town has properly awakened. I sauntered up near the church and drew this tiny chapel. I have drawn it before but the light was rather nice this time with unexpected shadows. The chapel is actually in the shadow of a large building behind it.

St Malo, France, pen and ink, drawing

We did not have much time so after a restorative coffee I sat and drew the goings on in the main square. Didn’t give much thought to the composition but the tree cutting the bike sort of works OK.

The next morning I painted a truly execrable scene looking down the road by the hotel which I duly scrubbed off. I decided to cycle off and look at the nearby town of Noix in the salt marshes. I just took my watercolours.

Il de Re, marshes, watercolour

I soon ran into a problem. Plenty of subjects but the sun was merciless so finding any shade to paint them from was impossible. In the end I found a bench under a tree and just painted what I could see. Too hot for watercolour really the paint was drying instantly on both paper and palette. 7in by 4in Watercolour.

Noix, Il de Re, France, watercolour, plein air

This is the church at Noix, once again the shady painting spot decided the subject. I had had a couple of very cold and rather potent beers before I did this so was not quite as considered as I might have been! I could do no more that day my cycle ride back was like crossing the Sahara but hotter. Still I had reminded myself how the light here is so fierce and this caught a bit of that. 10in by 8in Watercolour.

Il de Re, France, oil painting, plein air

Next morning I tottered off early to the beach… rather hung over from the previous night. The light was gorgeous with some very unusual contrasts. I had to get in the dazzle part immediately after drawing out because I could see it was going to change very fast. I actually painted a little vignette of the reflections before blocking anything else in. Plein air is so often driven by conditions and you have to adjust your methods on the fly. Oils 12in by 7in.

The next watercolour was OK but very pedestrian… lost somehow, I think still in the hotel room, I am guessing it fell of the ledge and went behind the sofa… probably the best place for it!

St Martin, Oil painting, Il de Re, France, plein air

In the late afternoon I did this view in the town of St Martin. I have done this in watercolour and oils before. Had to be careful not to over do the section left and right to keep the focus on the tower.

St Martin, il de Re, France, Oil painting

This is the afternoon next day, I had a morning off painting. I had spotted this the day before and noted the time. The weather was unrelentingly hot and clear which I find hard to paint so the shadows and contrasts here were fun to do. 12in by 7in Oils.

Watercolour, painting, plein air, St Martin, Il de Re

I had a real battle with this one. I was initially taken by the contrast of the nearby shadowed area against the bright backdrop. I then proceeded to mess it up by washing in the sky too dark! In the end I washed the sky back with white and reinforced the shadows with pen. 10in by 5in Watercolour.

St martin, France, nocturne, oil painting

Here is this year’s obligatory nocturne. Such a race so no time for finesse. The pings of light could be cleaned up a bit maybe, but such fun to paint. 10in by 14in Oils.

Plein air, oil painting, St Martin, il de Re

I had a fight with this one. Good bits but doesn’t quite gel into a picture. A very good exercise though. Looking at the photos after I could see that there wasn’t really a painting there. It was however a view that could be painted from a delicious bit of shade with cold beers nearby… 16in by 10in Oils.

Cafe, St Martin, pen and Ink, drawing

I had intended to do some cafe paintings but got distracted somehow. At the last minute I set about drawing this after I noticed how the light was falling across the people and awnings.

Port en Bessin, france, plein air, Oils, painting

Our next stop was the fishing port of Port en Bessin. I should have waited a little longer before doing this, the light had improved a lot during the time I was working. 14in by 6in Oils.

Normandy, cliffs, pen and ink, drawing

This was along the cliffs North of the town. The light was flat but it was very pleasant sitting and drawing this.

port en Bessin, France, pen and ink, drawing

Next day was more bright, I had intended to do fishing boats but got distracted by this view, was right in the sun so a beer was needed after…

Port en Bessin, harbour, oil painting, plein air

I planned to do a view I had done before looking over the town. I arrived a bit too early for the light so I did this to pass the time. I became so engrossed that I went on too long and missed the light on my intended subject! Never mind this was at that moment probably the better picture. 12in by 7in Oils.

Bayeux, cathedral, Normandy, France, pen and ink, drawing

Last one, this is Bayeux cathedral. One of our party said there was a good view over the river and he wasn’t wrong! I wish I had not packed my oils away, but as I had a drawing was the only possibility.

That’s it, not as much work as I usually do on these trips but there was so much eating drinking and chatting to get done that I rather fell behind…

 

« Newer PostsOlder Posts »

Powered by WordPress

error: Content is protected !!