Cyberware designs, manufactures, and sells standard and custom 3D scanning systems and software.

Echo Reliefs

The following discussion does not include any references to the use of the Surface Tools feature of Echo or the gradlim command in attempts to improve the appearance of the transition zone between the periphery of a relief image surface with a background surface treatment. Both tools have been tried more recently, in combination with various other tools and with varying degrees of success. A discussion of their use is in progress.

See also Part I and Part II.

The quick and dirty procedure for proceeding from the point where you have just created a raw relief image is as follows:

1. Use rprop or rlogprop to achieve the desired relative compression of the raw relief depth data. The rlogprop command is invoked as follows:

   echo > rlog -option prop_max prop_min depth_hi depth_lo

   The option flag may be set to -r or -t in which case all depths greater than depth_hi will be proportioned by the percentage factor prop_max, all depths less than depth_lo will be proportioned by the factor prop_min and all depths lying between depth_hi and depth_lo will be proportioned by a factor which varies either linearly ( -r ) or sinusoidally ( -t ) from prop_max at depth_hi to prop_min at depth_lo.

   The general idea is to retain more of the depth separation of foreground features than for those features near the periphery, which need to blend into any sort of synthetic background surface. For a face-on relief, for example, try depth_hi at about the bridge of the nose and depth_lo at about the back of the ear.

2. Meter several points around the periphery of the proportioned image to get a feel for the elevation at which you would like the background to lie. I like to shift the image in depth using the rincr command so that the desired background elevation is shifted to the zero plane. At this point save the proportioned and shifted image.

   BUG ALERT:
   Using the -c and -r options with the border command under release 2.0 causes the numerical arguments to be assigned inappropriately. Since the -c (circular/elliptical) option is set by default, the arguments are assigned correctly as long as you omit the -c. Refer to the draft discussion of relief preparation instructions if you want or need to create rectangular borders and backgrounds.

3. Void the resident image using intset. Start off with a flat circular background with bordering rim using the following technique. First, you can fool the border command into making a circular disc by making the border's rim wider than half the overall width of the current image, i.e.,

   echo > bord 0 0 250000

   Even if you wind up with a hole in the middle it won't matter because when you paste in the proportioned relief it will cover the hole. After creating the disc you can then create your bordering rim as described in the Echo command descriptions. For example,

   echo > border 0 20000 5000

   will set the lower inner lip of the bordering rim at 0, the rim's top surface at 20000 and the rim's width will be 5000 microns (5mm). You could save this "template" but its easy to recreate it if need arises.

   On the other hand, if you want a rectangular border, you need to specify the -r option when using the border command. This will result in the creation of a rectangular rather than circular border. The procedure for specifying the various arguments to the border command will be exactly analogous to that used above in creating the circular bordered flat background. An alternate, perhaps even simpler way of generating rectangular borders might be to employ the standard Echo commands latitude/longitude range, intset, extset, etc.

4. At this point you should begin to compose the composite image by using the paste command, first with the -n option followed by its use with the -v option. The command

   echo > paste -n filename

   will generate within the currently resident image a void region which is the negative or silhouette of the relief image saved as filename. This then allows the command

   echo > paste -v filename

   to replace filename's silhouette with filename's actual image. Try it, you'll probably like it.

   Now study your result particularly with regard to the match between the irregular relief image boundary features and the background. If the background appears to be too high or low, meter enough points to judge the average mismatch and then repeat the two foregoing paste commands but with one additional command between paste operations. After the first paste, which is like pulling the relief image out of a puzzle, raise or lower the resulting resident image by the amount estimated above using the rincr command. Now do the second paste operation, which replaces the missing piece of the puzzle but with a better match between image and background.

The combined image should now be a satisfactory albeit "stiff" version of a coin or cameo that can be scaled, proportioned, smoothed, etc. A somewhat more stylish treatment can be achieved by trying one or more of the techniques that have been employed for improving the aesthetics of the transition region between the relief image and the background.

The simplest of these techniques is to subject the composite relief to an aggressive smoothing operation such as would result from the command

echo > rep 3 smooth -p 2 2

This will soften the rim considerably but more importantly it will greatly improve the areas of the product at the transition from background to the actual image.

An even more effective treatment of this transition zone would result from using the Select Points=>Void Selected provisions of the Surface Tools feature. Removal of a band of points around the periphery of the image followed by one or more selective uses of the fill command will result in a wider transition zone between image and background. The subsequent smoothing operation is then even more effective in reducing the severity of the more obvious mismatches in elevation between the image periphery and the background.

In either event, once this latter smoothing operation is accomplished, the saved, unsmoothed image portion will need to be re-embedded using the two-step procedure involving the paste command.

I hope this will get you rolling and encourage you to try some of the embellishments described in the draft write-up. Better yet, invent some of your own, we've only scratched the surface. Good luck...... Ron.