Archive for November, 2011

Photoshop and Perspective part II: Creating reusable tools.

First of all, belated happy Thanksgiving to all who celebrated it last week.  I’m back now, and ready to pick up where we left off.

Not fully satisfied with the lengths I took previously in exploring the possibilities of perspective tools in Photoshop, I decided to create some more that hopefully have broader application.

For example, what about 4-point unlimited perspective?  Creating scenes with wide angles is immensely useful for fitting in a large amount of information in a confined space.  In addition, unlike drawing with two-point or 3-point perspective, there is no fussing about where to put the vanishing points (maintaining a believable perspective with those techniques as one moves and adjusts the vanishing points is more difficult as the distance between them changes non-linearly.  4-point perspective maintains  the same distance between VP’s by curving perspective lines).

Doing this exercise once and well, provides a digital artist with a reusable tool that can be dragged, dropped and scaled into frame ready for composition.

We’re going to be operating in Photoshop again, so bring up a window and create a new, high resolution file and guide layout similar to what you see here:

The horizontal and vertical guides should cut across and down the middle and bisect the workspace.  The horizontal line is your horizon, so draw a line across it using whatever method you prefer, as long as its straight.

Now, create a new layer and using the shape tool, make a perfectly circular path that touches the four edges.  Turning on the grid helps here.  Make sure the output is set to paths (not shape layers or fill pixels) in the options bar.  Briefly switch out to your brush tool and check the size of the brush as it’s the one that we’ll be stroking the paths with.  If it’s satisfactory, switch to the direct selection tool, select the path, right click on it and select ‘stroke path’ followed by making sure the brush tool is selected from the drop down menu in the pop-up.  Now the screen looks like this:

Before going on, let’s rename the path to something more specific than “work path”.  Doing this is also just good  practice as the work path gets overwritten each time a new path is made and we’ll be wanting to reuse this circle over and over again as we will see shortly.

Now, let’s move the circle precisely by selecting the path using Edit: Free Transform Path tool, and clicking the Use Relative Positioning option  represented by the small triangle icon in the options bar, zeroing out the x and y position values.  Pick a value for changing the vertical (Y) position and enter it into the Y position in the options bar.  Remember, this gap you are creating between the circle you just traced and the current one you are about to will be the constant unit of distance/depth in the resulting perspective template represented by all future circles, so keep this in mind.  I’m using -375 pixels in this case (though yours may vary) because I’m going to concentrate on creating the graph on the lower half of the image and then mirroring it upwards after I’m done.  If you want to approach it the other way from the top down, that’s fine, just enter your displacing values as positive numbers rather than negative.

Before proceeding, check to make sure that you’ve fixed the aspect ratio option (chain icon) in the options bar, and while clicking and dragging over the W: or H: scale entry, dynamically scale the circle path so it again passes through the points where the horizon and side image boundaries meet.  Like this:

After confirming the transformation, go back to the direct selection tool, right click on the path and stroke it again as before.

Keep repeating this process until the number of desired units measured towards the horizon is reached.  I’ll show eight iterations here for illustration:

Now this produces a bunch of pixels outside of the image plane that both take up extra space, and will hamper our attempts to mirror these lines up to the top half, so using a box selection, take everything below the horizon (snaps-on helps) and create a layer mask for the layer we’ve just put all these lovely lines on, then right click on the layer mask in the layer palette, and hit apply layer mask.  This should get rid of all the excess information we don’t need.
Duplicating the layer, mirroring the part below the horizon to the part above yields:

Not too far to go now.  Merge the two curve layers together and duplicate that layer, and follow that by enlarging the canvas size horizontally by 150%.  Move the newly duplicated layer so that the left vanishing point is now directly over the center of the original circle (where the guides meet) and create a new guide marking the center of the circle in the duplicate layer just shifted.

Repeat the process again, expanding the horizontal canvas size, this time by 133.3333% and duplicating  another circle layer.  Move it the same as before with the vanishing point of the new circle aligning with the center of the previous.
Now you have vanishing points for all directions, North, South, East, and West, with the sides of the canvas and the VP’s landing on them, the same direction in a 360 degree panorama.

For appearances and for added usefulness, we can duplicate the circle layer twice more and center them on the left and right borders of the image.

Just the cleanup remains.  Flatten all the circle layers to one, select all, create layer mask, and apply layer mask.

This is a quick and dirty example, but with a little more time and care, I produced a higher resolution one a couple weeks ago…

Once done, you can drop this into any background in your drawing program that you like, and move it around to get just the right composition.  Distracting distortions in drawing only become evident if you raise or lower the horizon too far from the center of the drawing you’re working on, exposing too much of the lower or upper planes.  Otherwise, panning left to right provides innumerable opportunities to utilize.

Information and sources of inspiration for this post came in part from Vanishing Point: Perspective for Comics From the Ground Up.

Good luck and keep drawing.


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Paradigm shifting.

Observation: arts of very different stripes and colors have a very important shared demand of their students : the ability to see things differently than most people perceive or are consciously aware of in day-to-day life.
Case in point:  The visual arts aren’t the only art I’ve had the pleasure to take up, and among the others is the martial art of Aikido.  But in both I’ve noticed something happened, and the way you react to your environment changes and you begin to perceive the way things are just a little differently, just enough to be able to accomplish the goal of both efficiently and fluidly.
Aikido depends on taking the momentum of an attacker and turning it against them.  But doing this effectively means having to resist the instinctive desire to well, resist.  Aikido is not a contest of strength, but if you keep the attacker at arms length and your balance.  You’re just essentially waiting for him to give you something useful, and it will happen if you let it.  It’s just not the way most of our minds work to just “go with it”.  This is exactly as it was presented to me when I began as a white belt many, many, hours ago.

Similarly for most of us working in the visual arts, seeing something as both flat (the piece of paper) and as having depth at the same time (the illusion of drawing) does not come naturally.  Anyone can see with their eyes intuitively the illusion of depth and understand what it is they’re seeing as a representation, but understanding how to make it so is another matter entirely, one that requires the duality of flat and deep to be understood on a conscious level, because art is created consciously.
Getting beyond both of these obstacles, and obstacles to understanding in general, have a good deal to do with us getting over the idea that we know by intuition, instinct, and dare I say by even our own personal experience, the best way to proceed, because there’s always  more than one way to skin a cat, as the saying goes.

There’s one other thing that both the visual arts and Aikido share: you can know some things, but never to the point where you can say it’s ever truly ‘enough’.

Keep it humble.

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World building epiphanies.

Today I have need to create a texture map for a planet to be rendered in Maya and since I’ve never done that before, I figured I would be remiss if I didn’t at least invite the rest of you along for the ride.

What I was looking for was a way to build my own planet with its own unique land and ocean formations.  Luckily there are a few resources already out there.  A little Google-fu led me to a site which mentioned in passing the name:” An Advanced Guide to planet creation” which, as titled gives a pretty good primer for getting started in the process without being so restrictive as to suggest that this method was the end-all method.  Some of these techniques I already knew of just from years of playing with Photoshop.

Then I recalled this video I watched last month on some rather unique ways one can use the new content-aware fill feature in Photoshop and that’s when the epiphany hit me.  Because now with a few satellite images swiped from NASA’s website, one can bring together the two aspects of what I consider to be really good creative art: Abstract design and a grounding in reality.

But I’m getting ahead of myself a little bit.  Let’s start with the following image:

As you can see here, I’ve chosen to start with a background that isn’t a topological reference at all, but a grungy texture I had in my personal image library.  It’s close enough yet alien enough to serve as a good starting point.

Then, I went and grabbed one those NASA satellite topological photos of the Grand Canyon and put it on its own layer, shrunk it down and then proceeded to use the lasso tool to pick off a general area I wanted to apply the canyon’s texture to thus:

And within a couple of trial-and-error attempts with the content aware fill, that space was filled with the following pixels:

Now if I choose to, I can get rid of the original square-cropped canyon part, but that may not be advisable just yet because simply by keeping that selection and using new-layer-via-cut, I can repeat the process over and over again sporadically, each time with a slightly different generation of canyon texture and shape.  To put a cap on this iteration however, we’ll just blend the results by altering the blend mode and opacity for the layer.

Even though I started out by using a base texture, I didn’t have to.  Were I to say, want to create continents of various shapes and dimensions, all I need do is create a jigsaw puzzle of selection areas and as long as the samples I’ve imported are located somewhere in the same layer, using “fill content aware” will create a texture in the shape of the selection you’ve made, for land or sea (though I recommend creating the land portions first and using images of coastlines for oceans so that the fill command has some point of reference for creating the fictional coastline).  That’s the long of it.  The short of it is this:

Followed by this:


Photoshop and Perspective

Every now and then, a question plagues my mind over why something hasn’t been explained before, or if it has, why nobody seems to have thought to share it with others that it could be found with a little Google-fu.
One of those that keeps coming back to me is why hasn’t anyone put out a means of quickly finding perspective planes and features using Photoshop?  Sure there are bits and pieces of information about using perspective in Photoshop as it pertains to painting on perspective planes inside existing photos, like picking off data points for the side of a barn and then using the brush tool to draw as if you’re drawing on the wall itself, but this isn’t so helpful when you’re starting from scratch.

Now if all you’re after is a quick 2-pt perspective for a single object with one orientation, then you can rough in perspective lines fairly well just by picking out two vanishing points at a reasonable distance and drawing a bunch of lines emanating from them like this:

Freebird! I mean "freehand"...

…and putting it on its own layer to keep it separate from the drawing proper.  I picked that one up from Michael Matessi’s Drawing Force website, but it’s a fairly standard trick, and a good one.
But say you’re constructing a scene where not everything is oriented along the same perspective lines.  Reality is more varied than that and if you’re creating a scene that incorporates more than one set of  VP’s (vanishing points)  for different objects/characters, then I have figured out relatively quick means of establishing some guides to quickly get you on your way.

Open up Photoshop and begin by making sure the rulers and snaps are turned on, then drag a guide down from the top ruler and use this as your horizon line.  Place it wherever your scene dictates it should be.

Next, use the pen tool in its ‘shape layers’ mode to draw a triangle with two of its points located along the horizon/guide and the third located below (or above depending on the need) in such a way that the angle it forms is eyeballed as close to 90 degrees as you can, like this:

Note that it’s important to keep one VP inside the print image area at this point because of a Photoshop quirk I’ll get into later.

Next, open up Photoshop’s measurement tool and draw a measurement line from the left VP down to the bottom vertex of the triangle.  Alt-click over the same vertex and extend a second measurement  line back up to the horizon line near where the right VP is.  It should snap to the horizon.  Adjust the position of the measurement endpoint left or right along the horizon until the angle it reads on the options bar reads 90 degrees and then snap a new guide to this location as seen here:

You can’t skip this step, because the moment you switch to the Direct Selection tool (next step), the measurement tool lines disappear.

Now you can switch to the Direct Selection tool, pick the triangle shape itself, and adjust the right VP to the intersection of the horizon guide and the vertical guide you just created.  Your triangle has now been ‘calibrated’.

At this point, you may want to establish the Diagonal Vanishing point (as it’s very useful to have as you already know if you’ve worked in perspective drawing for any length of time)  by bisecting the bottom angle of the triangle and finding where that meets the horizon line.  You can do this easily now by repeating the process above with the measuring tool but using 45 degrees as your target angle to hit.  Like this:

You can mark any of these points on their own layer now and label them if need be.  I used circle shape layers to mark these points, but you’re free to use a different marking method as you like it.  I would however, use layer-linking to ensure that all the work you just did on creating that triangle shape stays oriented with the labeling layer(s).  Just makes sense.  Also good for keeping all of this organized is creating a folder to store the layers in, which keeps clutter and layer-searching to a minimum.  This is how my screen looks now:

Now, what’s really great about this setup is that you can scale all of this prep work, move it to new locations and pretty much duplicate and dissect individual elements to create new perspective guidelines.  However, I would hold off on moving and scaling all of the components together until you’re finished establishing all the different perspective sets you need.  The objects scale, but the guides you’ve been using do not.  Keep this in mind.

If for example,  you wish to have a different set of points set up for an object oriented differently, copy the triangle you created earlier, and change its color to distinguish it from the first.  Next, use the transform path tool to rotate the new triangle to the orientation you want to draw the second object in, but just remember to move the center of the transformation to the triangle’s base.  This keeps all the elements in the final piece looking like they belong in the same space.  If it helps, you can pull a new set of guides off of the rulers to maintain the same bottom vertex for the triangle as seen here:

Notice that by rotating the triangle like this, one leg ends up crossing the horizon line while the other one drops below it.   Using the Direct Selection tool, select the two endpoints of this line and scale them similarly to how we rotated it above, by moving the center of scaling to the bottom vertex.  Make sure you keep scaling it until it too crosses the horizon line.  Remember, we’re only scaling the one leg and it should scale only along it’s length, like this:

Create a new pair of vertical guides that as closely as possible locates the intersection between the legs of the triangle and the horizon line.  Move the two upper vertices of the triangle to these intersection points and your new perspective orientation has been established, seen here along with the first orientation in grey:

At some point along the way, if it makes it easier, you can expand the canvas size so that all of your construction triangles fall within the canvas boundaries.  This makes it easier to use the measurement tool, as it sometimes has issues measuring angles for points outside of the canvas.

Now you can find the new Diagonal Vanishing Point (DVP) for the new triangle using the same method used above.

Fully labeled and organized, you should end up with something looking like this:

All of the layers are linked, to keep them consistent.  Now using the line tool, and snapping to the guide intersections, I can now freehand a grid for both orientations on respective layers thus:

This is still somewhat confusing as it’s currently set up, so let’s create a new group to hold both sets of perspective orientations, and create a vector mask for that group in the proportions of our final page output.  In this case, 8.5×11.  I’ve cropped the overall image for clarity but because of the abundant usage of vectors, there is minimal information lost.  Notice how the vector mask allows you to search for optimal framing.  It’s never a bad idea to experiment with different framing schemes even if you started out with something specific in mind earlier.  You can always find something better and unexpected.  Here’s what our final setup looks like:

Now we can finally start drawing with our new references, turning the relevant layers on and off to suit the object we’re drawing at any given time, and we can also adjust the opacity so the visual stimulus doesn’t become overwhelming.
Here’s a quick doodle completed with the aid of the setup.  The red box was done with the second perspective points and the figure and steps done with the first set.

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