Next example
Many may say that this cube is drawn correctly. In my humble opinion, this cube is drawn from a photograph. The horizon of the photograph on which this cube was drawn is much lower than the horizon of the platform on which this drawing is drawn. Therefore, I get the impression that the cube is very distorted. In my humble opinion, a preliminary photograph of this cube was taken from a lower point, and from a closer distance than the viewer looks at this picture. Therefore, the top face of the cube, I see not parallel to the floor surface. In my opinion, the top face of the cube is strongly inclined from the viewer.
To prove my point, a rectangular tile on the floor in this room helps me. We continue the seams of the rectangular tiles, and find the horizon of this site.
Now we find the horizon of the original photograph of the cube from which this drawing was made. The horizon of the cube (parallelepiped) can be found by continuing the horizontal sides of the cube if these sides are on the surface of the site or parallel to the surface of the site. Continue the horizontal sides of the cube until they intersect with each other. The continuation of the horizontal sides of the cube intersects at the horizon line of the photograph with which the cube was drawn. As you can see the horizon of the site and the horizon of the photo of the cube do much not coincide.
The top picture is the original.
In the bottom picture.
The cube is drawn so that its horizon coincides with the horizon of the site. In this case, the top face of the cube looks parallel to the floor surface of the room. Something like this should look like a cube drawn according to the laws of perspective (geometry), and not according to a photograph. Try to quickly look from the top picture to the bottom picture. Distortion of perspective becomes apparent. In any case, I can see.
The top picture is the original.
In the bottom picture.
The original cube is left, but a new area is drawn with the horizon matching the horizon of the cube. This is what the photograph used to draw this cube looked like.
There remains one POSSIBLE “mistake” – the mismatch between the distance from which the cube was photographed and the distance from which the viewer looks at the picture. That is why I have the impression that the near corner of the base of the cube is not straight, but sharp. Such a “mistake” can be obtained because the cube was photographed from a closer distance than the viewer looks at the drawing of the cube.
This possible “mistake” could be easily verified if the seams of the rectangular tile were parallel to one of the sides of the base of the cube. But in this figure, the seams of the tile are not parallel to the sides of the base of the cube, and it is not possible to check this possible error. Also, this possible “mistake” could be checked if the plates on the floor were square, but the plates on the floor of this room were not square, but rectangular.
How to draw a cube and the shadow of a cube correctly will be described and illustrated in detail in of this course. Or in one of the lessons on my Patreon page.
https://www.patreon.com/ArtistFarit
In the chapter or exercise “Parallelepipeds.”
Next example
A large cube made of small cubes. In terms of painting, the cube is drawn wonderfully. From a perspective point of view, the cube is drawn with small errors.
The cube is drawn on a rectangular paving slab. Continuing the seams of the tiles, we find the horizon line of this site. Tile seams intersect at the site’s skyline.
Continuing the horizontal sides of the cube, we find the horizon of the original photo (or sketch) of the cube. The horizon of the site and the horizon of the photograph, or the sketch on which the drawing was drawn, do not match. The discrepancy of the horizon lines is insignificant, but noticeable.
The discrepancy between the horizon line of the site and the horizon of the drawn object is not the only way to prove that the cube is drawn with slight violations of the laws of perspective.
In this photograph there is further evidence that the drawing is drawn from a photograph, or from a sketch. But not a way to build a projection.
Look at the right angle of the paving slabs and the “right angle” of the bottom face of the cube. Agree that all the corners of the bottom face of the cube should be straight (90 degrees). Unless, of course, a cube is drawn in this figure, and not a prism with a base in the form of a rhombus or parallelogram. The closest to us (and any) corner of the base of the cube should be straight. What do we see in the picture (and in the picture of the picture)? The pavement tile is rectangular, of which I have no doubt. It turns out that for the drawn cube, the angle closest to us is not a straight line, not 90 degrees. It can be assumed that the near corner does not lie on the surface, but hangs above the surface. In this case, under the cube, there should be a shadow. There is no shadow in the figure, which means that a cube is drawn that lies on the surface with its entire base.
Why do you get such errors?
First reason.
The cube is photographed (or drawn) at an angle slightly different from the viewing angle of the picture.
Second reason.
The photograph of the cube was also taken from a different distance that does not coincide with the distance from the drawing to the viewer. Or the sketch was drawn “by eye” without taking into account the laws of perspective.
The following figure shows three options for the relationship, the distance from which the 3D drawing of the cube was photographed, and the distance from the camera to the cube in the preliminary photograph or sketch.