SOOOO..... why do you need to use a Vector Mask??
Well I used this technique on the monthly challenge and so I will demonstrate a good use of vector masks for mapping.
I wanted all the objects in the map to resemble each other and maintain a semblance of uniformity.
So lets get right into it. For my original map I used quite a few layers for the stonework, but for this mini-tut I we'll be using a lot less. I also used nothing but brushes but again, for simplicities sake, we'll be using textures. Create your new file (As above tutorial instructed) Create a new layer which will name "stone" and well do it simple this time and Edit>Fill>Pattern and choose a nice rock pattern. Then go to Layer>Vector Mask>Hide All.
I used a backdrop on my original, but we are going to freehand some objects this time around. Grab the pen tool, make sure your path option is chosen and that you have Add to Selection marked. You'll notice that unlike a layer mask, your thumbnail of the layer as well as the mask will be selected at the same time. (Rasterized Layer Masks you either select the mask or the layer). So make sure your have the Vector mask selected as well and start laying down som straight line objects. If you want to get fancy, drop down a circle or two... up to you. Throw down a shape or two... HAVE SOME FUN!
Now create another layer "Overlay" and set it to overlay. Hold down the ALT key and LCdrag the vector mask to the new layer, making a copy of it.
Chose you a rough brush like a stipple brush, set your brush settings to pen pressure, min size halfway up, angle jitter 90%, click on the color dynamics, run the jitter up about 90%, brightness of 15%. Make sure your vector layer is unclicked, choose some nice ugly colors like (r177 g198 b84) and (r129 g129 b84) and start swathing the rocks and symbols you created.
Now create a new layer "Edge" and ALT copy the vector layer as before. Right Click on that vector mask and choose Rasterize Vector Mask,Right click the mask and choose "Add mask to Selection" With the mask still selected go to Filter>Blur>Gaussian Blur with 12 pix radius. (Now get ready for some fun) Filter>Blur>Gaussian Blur with 9 px, CTRL+F to run it again, then Filter>Blur>Gaussian Blur 6px, CTRL+F to run it again. Filter>Blur>Gaussian Blur 3px. (Whew... glad that was done huh?... I have an action command set up to do this as it works well when rendering logos and text), Now select the Layer thumbnail and not the mask, make Black your foreground color and the ALT+Backspace to fill the selection .... set the layer to Overlay .... You can adjust the opacity if you think it is too dark...
I filled the background with a dark gray in the final picture so you could see it a bit better.
Congratulations.. you just made some rocks
I'm sure however that you can see that many applications that vector masks will have to mapping.