If you're starting in the Library module, click on the photo you wish to process, and then press D to go to the Develop module (or click Develop on the top right menu). The first step is to correct any lens imperfections by going to the Lens Corrections panel, choosing the Profile tab and checking the "Enable Profile Corrections" box, as shown below:
Lightroom has automatically picked up my lens model and corrected vignetting and distortion corresponding to the shooting parameters of the particular photo. Distortion corrections are extremely important, as straight lines that initially appear curved due to the dreaded lens barrel become straight, setting the basis for following geometric corrections. Notice that I have also checked the "Remove Chromatic Aberration" box. It does not have any geometric effect but controls color fringing along hard edges, and improves overall photo quality. If your camera lens combo is not in Lightrooms lens profiles, you will have to correct barrel distortion manually, something I would like to explore together with manual geometric transformations in a dedicated article.
The next step is to go to the Transform panel. This is where all geometric transformations take a place in Lightroom, so it is fair to start with a brief description.
The top part of the panel labeled as "Upright" has five buttons (plus the Off button) that refer to different types of automatic or semi-automatic corrections. The Vertical button takes edges that are supposed to be vertical and makes them truly vertical. It is the auto adjustment worth trying in almost any buildings photo! The Full button will align both vertical and horizontal edges, ideal for head-on photos. The Auto button uses a sort of AI that will result in a milder adjustment (usually with near vertical edges) than the Vertical and Full buttons. The Level button aligns the photo along horizontal lines and has extremely limited to no useful value for buildings. The Guided button is the semi-auto solution that I was talking about earlier and will almost always get you out of sticky situations where all other auto methods have failed.
To ease your assessment it is quite helpful to use a reference grid on top of the photo. To switch the grid on/off use the shortcut Ctrl-Alt-O (or Cmd-Opt-O for Mac) or go via the menus <View> <Loupe Overlay> <Grid>. When the grid is on, adjust the size and intensity of grid squares by keeping Ctrl (Cmd) pressed and dragging with the mouse on the words "Size" and "Opacity" that appear with values at the top of the photo. Now that we are all set, let's look at a typical photo we would like to correct:
It is easy to see that edges are not truly vertical or horizontal. This is the result of applying the Vertical adjustment:
Since the columns are thinner at the top, the Vertical button has trouble aligning correctly. Moreover the horizontal lines at the top create a feeling that the building is leaning to the right. Since this is a head-on photo, utilizing the Full adjustment provides us with a very acceptable result:
If we wanted to be very picky, the only minor issue here is a slight misalignment from horizontal in the steps at the bottom of the photo. Trying the Auto button again creates a pleasing result with near perfect geometry:
The adjustment buttons are there for you to try and find what works best. When you press one button it cancels the effects of the previous one and recalculates the geometry from start. Press the Off button and all changes are cancelled. The second example demonstrates the inability of auto adjustments to correct geometry in a satisfactory fashion. Here is our starting image:
And here are the results after vertical, full and auto adjustments respectively:
Each corrected photo has their own serious problems and I would not consider any of them as presentable by a really wide margin. That brings us to the Guided Upright, the feature of Lightroom that has literally saved me hundreds of hours of messing around with auto and manual adjustments. In fact it is so quick and effective that I generally use it without even resorting to the auto adjustments!
To access it just press on the Guided button, or press the Guided Tool icon on the top left of the Transform panel, or use the shortcut Shift-T. Initially nothing happens onscreen because you have to determine your own guidelines. You can draw a maximum of four lines, two vertical and two horizontal. Click on the start of a guideline and draw it to its end. A minimum of two vertical or two horizontal lines is needed for the photo to start taking shape. If you aim at just a vertical adjustment, draw two vertical guidelines. Do the same for horizontal alignments. A head-on photo, like the example here, needs four guidelines. To be meaningful, guidelines have to use reliable architectural features. Here is the result with the grid switched on and with the grid switched off so that you can see the guidelines I used (white lines with little squares at their ends):
It is a high quality result that demonstrates how the Guided Upright feature allows us to tackle almost any geometric correction task when every auto adjustment fails!
Geometric corrections are the bread and butter of real estate, hotel and architectural photography, therefore if you wish to work within the approved guidelines of those segments it is critical to learn how to take care of geometric corrections. The Guided Upright feature was added in Lightroom CC sometime in 2016, so if you do not use Lightroom CC and do a lot of post-processing, it is worth considering an upgrade to the subscription version.
About the Author: Dimitrios Matsoulis is an engineer that studied in the UK and has an industrial automation and solar energy background. His love for outdoor activities and photography has naturally led him to photo editing. He uses Lightroom and Photoshop for his own photography as well as freelancing. He lives in Greece and maintains his online presence via his personal photography blog, 500px and Instagram.