You're not talking about making them look like they have perspective, but truly isometric?

If you're not already in the 3D world with these things, there are a couple of Edit - Transform functions that can do it for you.

You can use Edit - Transform - Skew, then a bit of Free Transform to narrow the result to make something look like it's on an angle and be isometric (equal angles)...

You can use Edit - Transform - Perspective, then a bit of Free Transform shortening to give something the look of perspective...

-Noel

I think the OP means »no foreshortening« when they say »isometric«.

GameViewPoint, could you please post an example?

By the way Christoph, try saving your screen grabs as PNG files - the forum software doesn't botch up the red places as badly.

-Noel

Have you tried -30˚, -60˚, 0˚?

Rotate -45 degrees

Scale height by 72%

More flexibility than a transformed Smart Object?

But a lot less convenience in my opinion.

Edit: But in principle I think it should be achieveable in 3D – but I haven’t figured out the values yet, either.

You may want to review the Wikipedia entry on isometric projection to get some inspiration regarding the numbers you seek:

Excerpts:

An isometric view of an object can be obtained by choosing the viewing direction in a way that the angles between the projection of the x, y, and z axes are all the same, or 120°. For example when taking a cube, this is done by first looking straight towards one face. Next the cube is rotated ±45° about the vertical axis, followed by a rotation of approximately ±35.264° (precisely arcsin(tan 30°) or arctan(sin 45°) ) about the horizontal axis. Note that with the cube (see image) the perimeter of the 2D drawing is a perfect regular hexagon: all the black lines are of equal length and all the cube's faces are the same area. There is isometric paper that can be placed under your normal piece of drawing paper as an aid.

In a similar way an isometric view can be obtained for example in a 3D scene editor. Starting with the camera aligned parallel to the floor and aligned to the coordinate axes, it is first rotated downwards around the horizontal axes by about 35.264° as above, and then rotated ±45° around the vertical axis.

Not intended to be particularly helpful, just fooling around with Photoshop's 3D facilities some more, showing the difference between Orthographic and Perspective views.

-Noel