Correcting Leaning Buildings with Software

Most people, when they notice that their architectural photographs contain buildings that are apparently not vertical, turn to software to correct the perspective.

To illustrate this, here is a building taken with a Canon RF16 16mm lens, with no changes other than resizing.

It is an attractive building from the Jugendstil period, but the picture shows it learning unacceptably backwards, with the top apparently narrower than the base. This is because the camera is pointing upwards at an angle (Note that the vertical centre of the photo is at the level of the second balcony, rather than at the height of the photographer -- 6ft from the ground). The reasons for this are that the street is too narrow to allow me to move any further back, and I have no access to the upper floors of the building behind me, which would allow me to level the camera, while still pointing it at the second balcony

This is what happens when I click on Perspective in DXO PhotoLab 6:

The sides are now more or less parallel; but in achieving this the bottoms of the sides of the building have been moved inwards, and the resultant black triangles need to be cropped away, after which we are left with this:

The resullt is not very good, because I had to leave a black triangle at the bottom right in order to include the right hand edge of the building. Clearly a wider angle lens is required. This would leave more "spare image" on the edges to be cropped away after "fixing" the perspective. It should, however, be noted that moving pixels around in this way can easily have an effect on the clarity of the photo.

I had a go with a wider lens, this time a Laowa 12mm, standing in pretty much the same spot. Here is the result out of the camera:

With perspective correction:

Cropped:

The result is a little more natural, and I might make a few adjustments; but finally I prefer this view, taken at an angle with the 15mm lens:

In sum, a situation in which a lack of space in the street makes a satisfactory photo, with right angles where they should be, pretty impossible by means of software correction.

This is an extreme case, and a really good photo can probably only be taken from an upper floor of the building on my side of the street. (Even so, it is probably a lost cause because the view of the umbrella awnings would be from above!)

I used PhotoLab for this demonstration because this is what I have, but other software, like Photoshop, would give the same result.

There are cameras, like the Leica Q3, that can do the perspective correction in the camera, but they also have to crop the view.

David

Yes, I have done a lot of correcting in post. It takes a lot of discipline, luck and a wider lens, to leave enough space around the subject, to avoid strange crops and loss of important objects in the picture.

I notice that in these threads on "correcting perspective" ( a misnomer because they are not correcting perspective, simply changing the position of the centre of perspective), the question of why we like pictures better when the verticals are made vertical is rarely addressed.

We are much more tolerant of horizontal lines not all being horizontal, except that most people like to see the horizon as horizontal.

Because our onboard computer, behind our eyes corrects keystoning, and we expect to see vertical building lines represented vertically in a picture.

Ancient Greeks knew quite a bit about awesome architecture and pleasant perspective. They built their temples with slight but effectful deviations from being perfectly straight horizontal and vertical.
Photogs might learn from them. For a more pleasing image leave the verticals a wee bit uncorrected, e.g. leaning inwards ~1% like in the Parthenon.

So you are saying that our brains correct keystoning when we look at a building, but not when we look at a picture of a building?

If that is so, why?

Because we know a picture is a picture, and not an actual building. But pictures and drawings can still play tricks on our vision.

[deleted]

This occurs with extreme perspective effects, when we use lenses wider than 24mm, and is easy to tweak in post with some minimal correction. It does not apply so much to pictures without dramatic perspective correction.

They mostly used this trick to render the building taller and more massive to the viewer. The Duomo di Fidenza gets narrower towards the Altar, to make the building seem longer than it really is to those entering via the main door.

Duomo di Fidenza