Part 8 A Good Head On Your Shoulders

Well, the hard part is done and now it's time to complete the head and stick it on a pair of shoulders. If you're putting it on a body or planning on covering the base of the neck with clothing of some sort you don't have to bother making the shoulders like this, but a floating head looks kind of funny if it stops with the neck, so I'm making him into something more like a bust.

Detailed explanation below the video again.

Sorry, but I'm afraid it's going to be a while before I can move on to the next bit I had planned. Fortunately the teeth, gums, and tongue are going to be separate parts, so the head model itself is finished with the following video. 

Details

• We start by sealing up the eye cavity. Select the edge loop inside the eye.
• Extrude, translate into the head, and scale down.
• Turn off the Eyeball Layer.
• Flatten the extruded loop on the Z-Axis.
• Use Append Polygon Tool to close the back of the eye cavity. You may end up with a triangle, but since it's going to be hidden by an eyeball that's not something I worry about.
• Delete history, duplicate, and flip the head on the X-Axis.
• Freeze transformations. When you do this on a flipped object the normals always flip as well, so reverse the normals and delete history again.
• Select both halves, Combine: Mesh, and delete history again. If you don't delete history before and after combining meshes weird things can happen later. Maybe not every time but I've seen entire models ruined because a student forgot to do this.
• Select the vertices down the center and merge them.
• Soften edges and delete history.
• How's it look? It won't hurt to give your geometry one last check before moving on.
• Now we move on to the mouth cavity. From the inside of the head, select the inner edge loop on the mouth.
• Extrude, scale taller and wider, and translate the loop into the head.
• Adjust the vertices to keep them evenly spaced and the loop round.
• Extrude the loop again. Pull it in and scale it slightly larger. This is the back of the mouth cavity and should bow backwards so scale it down on Z until it reverses it's direction.
• Use Append to Polygon Tool to seal up the back of the mouth.
• Insert an edge loop across the appended polygons and snap the vertices on the end to the vertices of the middle edge on the side of the mouth cavity. Merge vertices.
• Adjust the geometry to remove any sharp edges.
• Turn the Eyeball Layer back on and make sure it's no longer set to Reference or Template.
• Select the LEye Group and add it to a new group (control g). The new group's pivot is in the Center Point, so you can duplicate and flip the group on the X-Axis. If you had flipped the LEye Group it would have mirrored itself across its pivot which is centered in the middle of the eyeball.
• Select the duplicated LEye Group and flip it's X-Scale back to positive one.
• Open the Outliner and open Group 2 (The duplicated group) and rename LEye to REye.
• Remove LEye and REye from Groups 1 and 2 and delete the empty groups.
• Select the edge loop at the base of the neck. With your image planes turned back on, scale the loop up to match the shoulders.
• Extrude, pull down, and scale it up to the maximum width of the shoulders. If you're like me, you won't have the shoulders in full view on your image planes, so you'll just have to make a guess. You can change it later if it doesn't look right.
• Flatten the bottom on Y.
• Add an edge loop to round out the shoulders and scale it up to round them out and adjust the geometry to keep it all evenly spaced.
• This is the last time I'm going to say this about the head: soften the edges and delete history. 

Part 7 Lend Me Your Ears

I hate making ears, I always have hated making ears, and I most likely will always continue to hate making ears. I have long supported the action of removing ears at birth and replacing them with simple metal cones just to make life easier for modelers, but I don't think that will catch on with the rest of society.

The following should give you an idea of what it takes to make an ear, but the exact details vary greatly depending on the shape of the ear you're making and the exact geometry you have where it connects. I try to keep it as low poly as I can but you often end up with more geometry in the ear than the head so you may spend a great deal of time adding and deleting edges to clear up triangles hidden in the back. Always remember: Undo is your bestest friend in the world.

Details

• You'll want to use your head for reference while placing vertices for the ear, but you don't want to select it by accident, so put it on its own layer.
• Set the layer to Template once you've settled on the geometry around the ear. I had to make a couple adjustments and add another edge loop first.
• Use Create Geometry Tool to outline the ear. In this case I only had two vertices on the head where the ear would attach at the front, so I only placed two vertices at the front and at the back. If there were three on the front I would have also placed three on the back. I also placed two on the top and the bottom, although I may split it vertically down the center later if I feel it needs the extra geometry.
• Center pivot and rotate the ear to match from the front view.
• Extrude the outside of the ear to give it some thickness.
• Extrude the inside of the ear, pull it towards the head and scale it down.
• Delete the center face that you just extruded as well as the faces on the front. I delete these to ensure that the front of the ear is flush with the side of the head. If you don't it tends to look like a Mr. Potatohead ear that just got slapped on.
  
  Also, make sure you pay attention to whether or not the earlobe is attached or not. If it's detached then the front of the earlobe not the front of the ear, so don't delete that polygon. It doesn't need to be flush with the head.
• Snap vertices to the head wherever it seems to make sense. You will end up with triangles here but they can be dealt with later. I managed to snap everything onto the vertices of a single polygon but it doesn't always work out like that.
• Many of your vertices have been snapped together on the ear so select them and merge them. Just the vertices on the ear, though. You can't attach them to the head yet. (Why, yes, that does tend to confuse a lot of students I've worked with a lot of the time.)
• Use Split Polygon Tool to break that great big polygon on the outside of your ear into quads. This is why you needed the same number of vertices at the back as at the front. Otherwise you'd end up with triangles.
• fix the triangles behind the ear. I can't tell you how to do this. It depends on the geometry. I suggest you save a version of this file and then just start experimenting if you're unsure about how to do this. Add edges and delete edges and see what works. This part always takes me the longest. In fact, I increased the playback of the video from double time to triple, just so you didn't have to flounder around for the entire ordeal. I also had a couple triangles along the front of the ear, but they went away pretty fast after a vertical split and a couple edges deleted.
• Select the faces on the outside of the ear and extrude them, scaling down. We'll match these with the inside edge of the ear. I'm not going to create all the geometry on the inside since I intend to do most of that later in ZBrush but I do like to outline the ridge that runs around the top and back of the ear and a little just above the lobe.
• Freeze transformations and delete history.
• Take your head layer out of template mode and delete any faces that stand between the inside of the head and the inside of the ear.
• Delete history on the head.
• Before you combine the meshes, check the normals on the ear. You may need to reverse them. I forgot to do this in the video and had to undo a few steps and fix that.
• Select the head and ear, combine the meshes, delete history, and merge vertices. If you can still see border edges then you forgot to reverse your normals.
• Soften edges and delete history again.
• I noticed a dark spot behind my ear. This happens sometimes when you have a lot of edges meeting in a single vertex, like what happens where the ear meets the head. I smoothed the head just to see if it stood out as much in a higher subdivision. It doesn't, so I think it'll be good enough for ZBrush and undo the smoothing. 

Part 6 Filling In A Few Blanks

We have the basic framework for most of the head completed so this next step is mostly just a matter of filling in what's left.

Once again a detailed list of the steps is beneath the video.  

Details

• Use Append to Polygon Tool to connect from geometry behind the eye rings to the geometry above the mouth and down the neck. This should form concentric rings from the top of the head down to the chin.
• Insert as many edge loops to the new faces to match them with the side of the nose. Snap and merge the matching vertices. Make sure you adjust the new edges to keep everything round from both the front and side views.
• Pay attention to the jawline and make sure your geometry maintains its shape, as this is a defining feature. Also match geometry along the front of the ear, keeping vertices at the top and bottom of where we'll attach it in the next part.
• I've done this next step a couple different ways. You need to connect the geometry below the edge from the corner of the eye to the back of the profile. If there are the same number of vertices in both places you could just append, which is how I started. I then realized this wouldn't work all the way, so I stopped at the two bottom edges on the neck. I could have just extruded like I do two steps later.
• Insert edge loops to fill out the neck and keep it rounded.
• Extrude the side of the face and match what you can to the back of the head. Adjust the unmatched vertices from the side view to keep the back of the head round and then add the missing edges to the profile. Snap the vertices from the extruded geometry to the profile.
• Insert edge loops and match them to the neck below. Once again, try to keep everything round. Merge vertices.
• I decided to add another edge along the profile before appending more polygons, inserting edge loops to the new polygons and rounding them and merging the vertices.
• Select the vertices that you originally extruded from the profile and snap them to the center line, starting from the back of the neck and working up to the brow ridge where you leave a triangle. Merge vertices.
• Close up the back of the head with the Append to Polygon Tool and adjust your vertices. You don't just want to keep everything round but the polygons need to be as close to squares as you can manages, so I had to shift things around a lot to keep them from being too distorted. Since I plan to take this into ZBrush, it's important that I keep the majority of my polygons with roughly the same size, so that I maintain roughly the same amount of detail for sculpting after I begin subdividing it.
• Once again I duplicated and flipped the head to get a better look at it, then deleted the extra half for now. One of my biggest concerns is usually that the forehead and skull may appear dented in the middle, but that wasn't the case this time. Instead I noticed that the mouth angles back to sharply and I had to pull a few vertices forward to fill it out a little and the side of the head was too flat. 

Part 5 A Nose By Any Other Name

The nose used to be my second least favorite part of modeling the head, but that's because I used to do it rather half haphazardly and I'd have to spend forever afterwords trying to fix the mess I'd made. Fortunately I got it down to a fairly straight forward process which I have demonstrated for you below.

A more detailed outline is beneath the video.

Details

• Select the edge on the tip of the nose
• From the front view, extrude this edge and pull it to right - not the widest part of the nose, but just to the left of that. From the side view, move it to the base of the nose.
• Snap the bottom vertex of the extruded edge to the hanging vertex we left after making the rings around the mouth way back in Part 2. Adjust the top vertex to match the image planes.
• Insert an edge loop in the middle of the face. This will become the side of the nostril. Move it into place in the front view and then in the side view. You may need to add more edges to better match the shape of the nose.
• Use the Append Polygon Tool to attach the side of the nostril to the profile.
• I plan on taking this into ZBrush eventually, so I want to minimize the number of triangles and stretched polygons. I ended up with both of them here, so I added another edge loop across these new faces and adjusted the vertices to even things out.
• Now that I have the general shape of the nose I can begin looking for ways to eventually connect it with the geometry around the eye. You may need to add or remove edges to the nose.
• If there are vertices in the nose close enough to the eye geometry that you can snap on to the other, do so, otherwise we'll have to wait a few steps to connect that geometry.
• Merge the vertex that you snapped from the nose to the mouth loop earlier and use Append Polygon Tool to fill in the area around the nostril.
• Select the new faces, extrude, and scale down to match the nostril. Extrude them into the nose. Some people leave this step out if they're taking this into ZBrush, but I prefer to do it here.
• Soften edges, freeze transformations, and delete history.
• Display face normals for both pieces of geometry. If the normals point inwards for either, reverse them and delete history again.
• Combine both meshes and delete history again. Always delete history before and after you combine meshes. If you don't weird stuff can happen later.
• Merge any vertices you were able to snap from the nose to the eye geometry.
• It's easier to see if there are any obvious problems with your head if you can look at it with both sides, so every now and then I duplicate and flip it across the X Axis by setting the X Scale to negative one. If nothing jumps out at you, then delete the extra half and go back to the original.
• Append the edges between the profile and the eye geometry.
• Append the edges between the eyes and the mouth.
• Insert edge loops as needed to match these new faces to the side of the nose.
• Snap and merge vertices.
• Adjust the geometry flesh out the cheek.
• Soften edges and delete history again. 

Part 4 Put A Lid On It

Unless you're modeling Marty Feldman, you're going to want some lids over those eyes.

More detailed instructions below the video.

Details

• Use Create Polygon Tool to outline the inner edge of the eyelids.
• Center Pivot and move in front of the eyeball.
• Select the edges and extrude them out. Delete the interior face.
• Select pairs of vertices and translate them back, fitting the geometry snugly against the eyeball with minimal interpenetration.
• To better match the geometry with the image plane I put the eyeball on its own layer and set that to Template to get it out of the way.
• In the video I selected the outer edges and extruded it out once, but you could put this off until after the next four steps.
• Insert edge loop inside the first ring of faces.
• Select the new vertices on the bottom half of the lid one by one, snap them against the vertices on the inner edge loop, and pull them forward ever so slightly to form a little ledge.
• Pull the new vertices on the top half of the lid forward to form a little peak.
• Adjust the vertices near the corners so that the top and bottom have a smooth transition.
• Let's return to the outer ring of edges. Towards the center of your head, the area around the eye flows forward to the bridge of the nose while the side flow backwards. Rotate the ring on the Y Axis to match this.
• Extrude out and rotate a second ring.
• From the side view, begin adjusting the geometry to better match your reference image.
• Extrude and adjust again. This is all dependent on the head you're making, so it may take some trial and error to get it just right.
• Select the top edges and extrude them up. You can either go up the the eyebrows and continue re-extruding - matching each line with the profile - until you reach the top of the head or go straight to the top and insert edge loops afterwords to match with the profile from the side.
• Keep the bottom of the new extrusions flush with the corner of the eye and spread out the rest of the vertices to keep the spacing even and edge loops round.
• The edge loop matched with the top of the head will be the widest part of the head so match that with the front view.
• In the video, I realized that my front and side IPs were off again, so I used the side view to position the vertices vertically and the front view for the width.
• Smooth edges, freeze transformations, and delete history. 

Part 3 Eye Can See You

Before you can begin making area around the eyes it helps to have the eyeball already in place. Today we're going to make a short deviation from Polygons and switch over to Surfaces.

Detailed instructions below the video.

Details

• Create a NURBS Primitive Sphere. If your sphere is displayed with straight edges then press 3.
• Rotate your sphere 90 degrees in the X direction so that the pole faces forward and center it over the middle of the front image plane's eye.
• Scale down the sphere. You may have to guess a bit here, since most of the eyeball tends to be covered by skin muscle and bone, but it should be a little larger than the eyelids. Now you can match up the front of the eyeball with the side image plane.
• Of course, the front of your eye isn't the front we've got here. A real eye has a little dome on the front called the cornea. Right click the sphere and select Isoparm.
• Click on one of the horizontal curves and drag it forward. This should mark the side of the iris.
• Then go to Edit Nurbs: Insert Isoparms.
• Repeat those steps several times in order to increase the geometry in that region.
• Select the CVs controlling the front of your eye and begin scaling and moving them to create a dome.
• Freeze transformations and delete history. I know I say to do this a lot, maybe even more than you need to, but I've seen history build up to the point where it slows down the computer.
• Now we return to Polygons to begin the iris. The iris is roughly toroidal in shape and located just behind the transparent cornea.
• Create a torus and reduce the geometry. You can smooth it later, but for now we don't want too much to work with.
• Scale it down along Y to flatten it out, rotate it 90 degrees on X, alight in with your front image plane, and scale it down to fit.
• Select the inner ring or two and scale them to match your pupil.
• Jumping back and forth between front and side views, begin moving and scaling rings of vertices to make the iris bow inward.
• Delete history and freeze transformation.
• While we're at it, let's take care of the UV layout as well with Create UVs: Planar Mapping option box. Project from Z Axis. Scale this down in the UV Editor. Delete history again.
• Make a new Lambert, call it Iris.
• I arbitrarily colored it brown, but I intend to replace that later with close up photo of an iris.
• Assign Iris to the torus.
• Name the torus LIris, since this is the Left Iris. For the same reason, let's name the sphere LEyeball.
• Create a new blinn and change the color to an off white.
• Assign it to LEyeball and name the blinn Eyeball.
• Although the pupil is just a hole in the eye in real life, we don't want to risk seeing the back of your sphere when we look through it, so we'll place a black object there to simulate it. It doesn't have to be much. Create a polygon sphere and reduce the geometry.
• Delete the top of the sphere.
• Scale it down and stretch it along its Y Axis.
• Rotate it 90 degrees on X and place it right behind the hole in the iris.
• Freeze transformations and delete history.
• Create a new lambert, change it to black, name it Pupil, and assign it to the dome.
• Name the dome LPupil.
• So you've got an iris and a pupil set up inside your eyeball, but what good is it going to do you if you can't see them? We need to make the cornea transparent but leave the rest of the eyeball opaque. Go back to your Hypershade and select Eyeball.
• Add a ramp to the transparency. The ramp only needs two colors, white and black. Change the type to a U Ramp so it faces the right direction. The white is transparent and you'll want it centered over the cornea but it's hard to do that if you can't see where it is.
• Return to the blinn controls and scroll down to find the Hardware Texturing tab. Open it up and click the Textured Chanel. If it doesn't give you any options then you'll have to save and restart Maya. That's an annoying glitch you'll have to get used to dealing with.
• Once you've got that sorted out, select Transparency from the drop down list. You eyeball will now display the transparency ramp instead of the colors.
• Now you can adjust the placement of the transparent region by moving the black and white controls in the ramp. ou'll want to check it out with a few test renders to make sure the cornea blends in to the rest of the eyeball while still covering the edge of the iris.
• The eyeball is wet and shiny, so it has a small, bright specular highlight. To get this effect with a blinn shader you have to reduce the eccentricity and increase both the specular roll off and the specular color.
• Around this point in the video, I realized that the pupil was still a bit too big, so I had to scale it down a bit more.
• When you look at an eye from a nearly side view, the iris appears to bulge out into the cornea. This is due to refraction. We don't have that yet. Go to your Render Settings and make sure Raytracing is checked.
• Under Eyeball's Raytrace Options, check Refractions.
• The index of refraction is a ratio between how fast light travels in a vacuum compared to how fast it moves in a given material. This difference in speeds determines how much it is bent from its original direction. According to this table, the cornea's Refractive Index is 1.38, so that's the value we input. You can always adjust it after some test renders if it doesn't quite work as expected.
• Turning on Raytracing also allows Reflectivity, which I don't want at the moment. I'll turn that off for now, since it's just a distraction. I can always bring it back later, but to a lesser extent.
• There's one more thing this ramp is good for. Select the ramp node in your Hypershade and shift select the eyeball.
• Click Edit: Convert to File Texture Option Box. Here you can save a tiff of the ramp in your images folder. You can use this to see where to put the veins when you're creating the eye's color map in Photoshop. You'll want them to fade out before you reach the cornea, unless you want some seriously bloodshot eyes. I won't go into the details of creating color maps here. I'd rather focus on modeling for the time being.
• This created new shaders which you don't really need. Reassign Eyeball to LEyeball.
• Select all three parts of the eye, freeze transformations, delete history, and group them.
• Modify: Center Pivot.
• Name this group LEye. 

Part 2 Beginning The Head

Ok, so you've got your image planes set up and are ready to go? Then we may begin modeling. Make sure you're in Polygon mode, since you won't find most of the tools I'm going to use in Animation or Surfaces, or anything like that. We'll start at the side view. It's usually best to work in the orthographic views and use the perspective view to check the results.

Detailed list of instructions below the video.

Details

• Go to Mesh: Create Polygon Tool. Starting at the front of the neck, trace up and around the profile of your head. There are two things to remember while doing this.
  
  1: keep the mouth open and make a mouth cavity. A lot of reference images may have a closed mouth, but try to estimate what it would look like if it was open just a little bit. If you want to animate it later, you'll need it this way.
  
  2: it's easier to start with a low poly object and add detail later, so don't worry about getting every nook and cranny, especially the mouth cavity, since you're going to delete most of it later.
• Ok, you've got a polygon silhouette of your head. This gives you a starting point for everything else. If you're anything like me you're going to need to go back and make some adjustments, since I tend to play it fast and loose, just to get the geometry started.
• Select the face (Right click Face, then select it) and extrude it.
• Switch to the Front View and pull the face to the side of the nose.
• Delete the two big inside and outside polygons, the long polygon on the bottom, and the mouth cavity except for the inside of the lips.
• Time to start on the mouth. Select the edges for the inside, top, and front of the bottom lip as well as the inside, bottom and front of the top lip.
• From the Front View, pull these to the corner of the mouth and scale it down to match the overall dimensions of the mouth.
• From the Side View, pull it back to match the corner of the mouth.
• Adjust the geometry to keep the inside of the lips pointed towards the center of where the mouth cavity will be, rather than just pointing straight back.
• Pull the top and bottom vertices on the front of the lips to the side, so their edges don't have any geometry between them.
• Use Edit Mesh: Append to Poly Tool to connect the top and bottom lips at the side.
• Now use Edit Mesh: Insert Edge Loop Tool to split these new polygons horizontally. Pull these new edges to the right and shape the geometry so the mouth has a corner.
• You can add vertical edges to the front of the lips now and round it out so it's no longer just a straight line to the corner of the mouth.
  
  (Around here I realized that my image planes still didn't quite match up, so take the layer off reference, move it up a little, and reset it.)
• You can also give the upper lip a little dip in the center, for the cupid's bow. The face I used has thin lips, so I didn't bother make this very pronounced.
• Now, select the outer edges (The ones that will be on the face, not inside the mouth) and extrude them. Pull these edges out to form a ring around the open mouth. Remember, the muscles around the mouth are concentric rings and you want to mirror that in your model.
• Select the vertices of the extruded geometry nearest the head outline and snap them to the appropriate vertex. (Press V and hold it as you move the vertex.)
• Continue extruding and snapping until you are one ring past the bottom of the nose. (It depends on how many splits you've got, which depends on the kind of face you're making) Do not snap that last, top vertex to the profile. Leave it loose. You'll need it to attach the nose later.
• Select the edges on the bottom half of your last ring, from the corner down. Extrude them, translate them down to the bottom front of the neck, and scale them down along the Y Axis to flatten them.
• Insert edge loops along the length of the new polygons and translate them to match up with the outline of the neck.
• Snap vertices to the profile. Be careful. If you snap them from the side view you may snap to the center line rather than the extrusion.
• Adjust the geometry from the front and side views to match the shape of the original head. This step varies from head to head, so you'll just have to play around with it until you like the way it looks. Check the perspective view constantly.
• When you snap vertices together, they're still separate. To highlight where these vertices are go to Display: Polygons: Border Edges.
• Drag select the vertices on the border edge and use Edit Mesh: Merge Vertices to seal everything up.
• Normals: Soften Edges.
• The normals are probably facing inward. Display: Polygons: Face Normals to check. If so, Normals: Reverse.
• Freeze Transformations and Delete History. 

Part 1 Getting started

Recreating a human head is one of the hardest things to do. Everyone knows what they look like and when you've done it wrong, but most people can't tell you what the actual problem is. That's why I'm such a big fan of Reference Material. You need good, clean, preferably high resolution front and side view photographs. Good images will be doubly useful, both for modeling and for creating an appropriate color map later.

There are plenty of places to find these images online. 3d.sk is an excellent source of human references. If you don't feel like spending money, then grab a camera and a friend who's willing to let you take a couple mug shots.

Also, I know this looks like a lot of text, but each part has a video. The text is just there to explain what I'm doing in the videos with more detail.

Preparing Your Reference

Now that you've got your pictures, you need to get them ready for Maya, because Maya likes square, 72 dpi tiffs, and chances are good your image isn't going to be square. Load them in your image editing software. I use Photoshop.

- Change the canvas size (Image: Canvas Size). If it's too wide, crop it down. If it's too tall, increase the width.

- Make sure the files are at 72 dpi (Image: Image Size).

- Scale and line up the images vertically, or at least as close as you can get. Copy one image onto a layer above the other image and decrease its opacity. Try to match up the hair line, eyes, nose, and mouth. Guidelines can be helpful here.

- Chances are the subject of your photograph didn't sit perfectly upright or even at the same angle between front and side shots, and the image will need to be rotated and scaled. Even then it may not be enough and you'll just have to use your own judgment when it's time to start modeling with them.

- You may want to select half the front view, copy it, and flip horizontal in order to make the face perfectly symmetrical, but since I only model half of the head and mirror it in Maya I don't usually bother.

- I suggest you save this as a psd, just in case you need it again later.

- Save out the front and side views as separate tiff files with no compression.

Image Planes

Now we can finally get to Maya!
Just one note before we get started. The naming convention I use for the materials and planes is not important. What's important is to have a naming convention and to remain consistent.

A more detailed list of instructions lies below the video.

Details 

• The very first thing you want to do is go to File and create a New Project. I can't tell you how many students I've seen get messed up because of this. Give it a name and tell it to use defaults for everything else.
• Move the psd file into the Images folder and the tifs into the Sourceimages folder. 
• In your preferences, change units to inches (or whatever you prefer working in). 
• Create a polygon plane with width and height the same as your image size, divisions of one, and name it FrontIP. 
• Rotate it 90 degrees on the X axis. Freeze transformations (Modify: Freeze Transformations) and delete history (Edit: Delete by type: History). 
• Make a new Lambert material and place your front image in the color channel. Assign it to the plane. 
• Name Lambert IPFront. 
• Duplicate the plane (ctrl d) and rotate it 90 degrees in the Y axis. Freeze transformations and delete history. Name it SideIP. 
• Make another Lambert material and place your side image in the color channel. Assign it to the new plane. 
• Name the new Lambert IPSide. 
• Select both planes. 
• Go to your Layer Editor and make a new layer. 
• Select your image planes, right click the layer and assign them to it. 
• Set the display type to Reference (Click the empty box next to the "V" in the layer until it says "R"). Now you can see them but not select them while you're modeling. 
• Name the layer IP (double click).