US2374981A

US2374981A - Carving method and projector

Info

Publication number: US2374981A
Application number: US411302A
Authority: US
Inventors: Cooke Hereward Lester
Original assignee: AERO SURVEY CORP
Current assignee: AERO SURVEY Corp
Priority date: 1941-09-18
Filing date: 1941-09-18
Publication date: 1945-05-01
Anticipated expiration: 1962-05-01

Description

y 1, 1945- H. L. COOKE CARVING METHOD AND PROJECTOR Filed Sept. 18, 1941' 3 Sheets-Sheet l K 5 mm m M m L AY .WB 12% z May 1, 1945. H. L. COOKE CARVING METHOD AND PROJECTOR Filed Sept. 18, 1941 3 Sheets-Sheet 2 INVENFR flE/QEWAED A. 0 0/65 ATTORNEYS May -1, 1945. H. COOKE I CARVING METHOD AND PROJECTOR 1941 3 Shegts-Sheet 3 Filed Sept l8 INVENTOR v f/s/esu/n an A (oaks mjbayr ATTORNEYS Patented May 1, 1945 OABVING METHOD AND PROJECTOR Hereward Lester Cooke, Princeton, N. 1., assignmto Aero Survey Corporation, a corporation of Delaware Application September 18, 1941, Serial No. 411,302

11 Claims.

In my United States Patent No. 1,980,981, I have disclosed a method and apparatus for shaping or carving relief models in accordance with with the optical or plastic image, the block thereupon constituting an exact three dimensional replica of the terrain shown in the photographs. In carving the block to correspond with the plastic image, some difllculty has been experienced in seeing or identifying the surface of the block so as to tell when it corresponds with the visible optical image. The object of the present invention is to obviate this diiiiculty.

The present invention relates to a method and apparatus for rendering the surface being shaped or carved clearly visible and identifiable. This is preferably accomplished by projecting spots of light or a pattern of bright rays upon the block being carved, which enables its surface to be identified and the position of the surface to be compared with the position of the projected optical or plastic image. The pattern of bright rays is preferably caused to vary either in intensity or position, or both, so as to facilitate the identification of the surface being carved.

In the accompanying drawings 1 have illustrated certain preferred forms of apparatus adapted for the performance of the method of the present invention. In these drawings:

Figure 1 is a diagrammatic side elevation, partly in vertical section, showing an apparatus for projecting spots of light upon the body to be shaped or carved.

Figure 2 is a plan view of part of the perforated movable disc through which the light is projected.

Figure 3 is a side elevation of a modified form of projection apparatus, parts being shown in vertical section.

Figure 4 is a plan view of the block being shaped or carved showing the area upon which the spots of light are being projected.

Figure 6 is a vertical sectional view of the projector shown in Figure 5 taken on line 6-5 of Figure 5.

Figure 7 is a sectional view on line 1-1 of Figure 6 showing the film gate or aperture plate and a, portion of the film.

Figure 8 is a plan view showing a portion of a modified form of film with grid markings thereon, and

Figure 9 is a diagrammatic perspective view showing a partially carved block and the projection apparatus for projecting the photographs thereon so as to form the optical plastic image, and also showing the projector of the present invention projecting a pattern of light upon the block.

Referring to the drawings in detail, Figure 9 shows a preferred general arrangement used in practicing the present invention. I5 and iii are two projectors, such as are shown in my Patent No. 1,980,981, or which may be the projectors of a Multiplex apparatus. Two overlapping photographs of the terrain are placed in these projectors which are adjusted to bring the photographs into stereoscopic relationship so that an optical plastic image I8 is produced which is located so as to appear to lie beneath the top surface of the block 20 of carvable material such as plaster of Paris. The plastic image may be rendered visible by the anaglyphic method. which comprises the projection of one of the photographs through a blue screen and the other photograph through a. red screen, whereupon the plastic image may be observed by use of a pair of glasses with red and blue lenses. If preferred, the flicker method described in my patent aforesaid may be employed in which the two photographs are alternately projected and viewed through a shutter which permits first one and then the other to be observed in rapid succession. This also produces a visible plastic image. The operator, observing the plastic image apparently below the surface of the block 20, then proceeds with suitable tools to carve or otherwise shape the block to conform with the optical plastic image projected by the projectors l5 and It. This operation is facilitated by providing means for rendering the surface upon which the work is being done clearly visible and identifiable so that it may be distinguished from the projected plastic image.

The preferred means employed for this purpose comprises what may be termed a pattern projector 25 which throws a bright pattern of Figure 5 is a plan view partly in section of light upon the surface of the block. The operathe projector shown in Figure 3.

tor is able to distinguish where this pattern falls .upon the surface being carved and is thereby enabled to carve away the surface of the block until such surface, identified by the pattern of light rays, coincides with the optical plastic image produced by the projection of the two photographs. In Figure 9 the pattern of light rays is indicated by the grid marks 21, 28 and 28. The block is indicated as being partly carved away, the marks '28 falling upon the original surface of the block, the marks 28 falling upon a partially carved surface, and the marks 21 falling upon a surface of the block which has been fully carved until it coincides with the optical plastic image I8.

The pattern projector 25 may be of any suitable form, a simple form being shown for instance in Figure 1. As here shown a standard 35 is mounted on a movable base 88 which is supported upon a table 31. Also supported on the table is a block of carvable material 38 which is placed under the projectors I5 and I6 (Fig. 9). Mounted on the standard 85 is a source of light, such as an electric light bulb 48, the beam from which passes through a condenser 42 and then through a movable plate, film or disk 44, which is provided with numerous transparent portions or perforations 46. (Fig. 2.) The disc 44 is mounted on a rotary shaft 48 driven by an electric motor 49 through suitable reduction gearin so that the disc 44 rotates at a slow speed. Preferably the speed of the motor may be varied in any suitable manner as by a rheostat indicated at 5|. The disc 44 is opaque, except for the numerous transparent spots or perforations 48, sothat a slowly travelling pattern of spots of light is projected by the projector. This pattern is projected upon the block 38 and as the beam of spots is usually projected at an angle it is desirable to provide an adjustable lens 53 mounted on a standard 54, the lens being angularly adjusted to produce the focusing of the attern of spots upon the carved surface of the block. The spots of light are preferably focused to be sharp at the average line of elevation of I the finished carving, such line being indicated at 56. In this way approximate sharpness of projection will be secured at all times. The adjustment of the lens 53 to secure this result occurs when the central transverse plane through the lens, indicated at 58, intersects the plane 58 of the disc 44 on a line 0 which lies in the average plane 58 of the carving.

The slow rotation of the disc 44 causes the pattern of spots to move slowly over the block being carved, and thereby enables this pattern, where it falls upon the surface of the block, to be clearly visible and distinguishable from the projected optical plastic image cast by the projectors I5 and I6, as shown in Figure 9. This pattern enables the carver at all times to identify the surface upon which he is working so that he can tell when the surface is approaching coincidence with the optical plastic image and when such coincidence is actually reached. In this way he is able readily to control his carving tools so as to produce a model which accurately conforms to the projected plastic image.

In Figures 3 to 7 a modified form of projector is shown in which the projector proper comprises a casing lu-mounted between the arms of a yoke I2 and capable of tilting adjustment about a horizontal axis, such adjustment being produced by turning the knurled discs I4 (Figure 5). The yoke 12 is pivotally mounted upon a rod 18 and may be loosened thereon for adjustment about a vertical axis by means of a knurled nut 11. The rod I6 is mounted for vertical adjustment in a standard I8 in which it may be held by a set screw 88.

In the casing 18 is a source of light, preferably an electric bulb 82 having a concentrated filament, producing an approximately point source of light. The light is projected through a suitable condenser 84, passes out of the casing through a film gate or aperture plate 88 and through a telescopic tube 88 at the lower end of which is mounted a block 88 in which is adjustably mounted a lens holder 92 carrying a lens 83. The lens holder and lens may be tilted by means of a knurled head 84. The outer section of the telescope tube carrying the block 88 is preferably provided with adjusting means such as a rack 85 engaged by a pinion 86 which may be rotated by means of a knurled head 98. The adjustment of the lens 88 by means of the

heads

98 and 94 permits the beam of patterned rays to be brought into proper focus upon the block being carved, as already described. For producing the pattern of rays an endless strip of opaque film I88 is preferably employed, the film being provided with a suitable transparent pattern such as the perforations shown at I8I in Figure '7. The film runs over a pair of idlers I 83 and I84 at the front end of the projector and over a driving sprocket I88 which is arranged to be driven at slow speed through suitable reduction gearing by an electric motor I88, the speed of which may be controlled by a rheostat H8. The run of film extending between the idlers I83 and I84 is transverse to the axis of the projected beam and is located between the condenser and the aperture plate 86.

In some instancesinstead of using a film or light interrupting member comprising a multiplicity of transparent spots or perforations, as indicated in Figures 2 and 7, the light interrupting member may be formed with a regular pattern preferably in the form of a grid of crossed transparent lines as indicated at H5 in Figure 8. Such a grid of lines produces a pattern which is very easily identified upon the surface being carved and enables the form of such surface during the carving to be readily identified. This pattern or grid of rays is preferably caused to travel slowly across the surface being carved in the manner already described.

An additional method which may be employed for enabling the pattern of light to be identified and distinguished from the projected optical plastic image, consists in varying the intensity of the light of the projected pattern. Means for accomplishing this are indicated in Figure 3 where a variable rheostat H8 is placed in the circuit of the light bulb 82. This rheostat can be constantly varied as by means of an electric motor I28 moving the rheostat core II9 through suitable reduction gearing so that a pattern of light is produced fluctuating or pulsating in in-' tensity. This enables the pattern to be readily distinguished from the plastic image projected by the projectors I5 and I6. With this pulsation of the light intensity it may be possible to dispense with the moving of the film or light interrupting member, although preferably both the moving film and the means for pulsating the intensity of light are employed.

By the use of the means for projecting spots or a pattern of rays upon the surface to be carved, which spots or pattern can be distinguished from the projected optical plastic image, it is possible to determine at all times the form of the surface being shaped or carved and to rapidly form such surface into coincidence with the optical plastic image, so as to produce an accurate three dimensional replica of the optical plastic image. The speed and accuracy of production of this replica is of the utmost importance particularly in the making of maps for military purposes.

While I have described in detail certain preferred procedures to be followed in practicing my invention which I have found to be convenient and practicable, and while I have illustrated and described in detail certain forms of apparatus which I have found well adapted to carrying out the required operation, I do not wish to be understood as limiting myself to the performance of the process in the precise manner set forth or the following of a particular sequence of operations where not essential to secure the intended result, or to the use of the particular apparatus as set forth in the specification, as I realize that changes both in procedure and in the apparatus are possible and I further intend each step or sequence of steps and each element or instrumentality apnearing in any of the following claims to be understood to refer to all equivalent steps, sequences of steps, elements or instrumentalities for accomplishing substantially the same result in substantially the same or equivalent manner.

I claim:

1. A method of producing a relief map which consists in projecting a pair of overlapping aerial photographs upon a block of material in such relationship as to produce an optical plastic image of terrain on the block, simultaneously projecting upon the block a pattern of light rays which can be distinguished from the optical plastic image and shaping the surface of the block to coincide with the optical plastic image.

2. In a projector of the character described, a casing containing a source of light and means for projecting light from said source in a concentrated beam, a support upon which said casing is mounted for angular adjustment, a telescopic lens support carrying a lens mounted in the axis of said beam, means for angularly adjusting said lens about an axis transverse to the axis of the beam, an endless opaque film movably mounted in said casing and having a run extending transversely of the axis of said beam, said film having small light transmitting areas, and means for driving said film.

3. In a projector of the character described a casing containing a source of light and means for projecting light from said source in a concentrated beam, a support upon which said casing is mounted for angular adjustment, a telescopic lens support carrying a lens mounted in the axis of said beam, means for angularly adjusting said lens about an axis transverse to the axis of the beam, an endless opaque film movably mounted centrated beam, a support upon which said casing is mounted for angular adjustment, a telescopic lens support carrying a lens mounted in the axis of said beam, means foriangularly adjusting said lens about an axis transverse to the axis of the beam, an endless opaque film movably mounted in said casing and having a run extending transversely of the axis of said beam, said film having light transmitting lines thereon forming a grid, and means for driving said film.

5. A method of producing a relief map which consists in projecting a pair of overlap ing aerial photographs on a block of material in such relationship as to produce an optical plastic image of terrain on the block, shaping the surface of the.

block to coincide with the optical plastic image, and producing on the partially shaped surface of the block a visible pattern distinguishable from the optical plastic image so as to enable the surface being worked on to be distinguished from the image being reproduced.

6. A method of producing a relief map which consists in projecting a pair of overlapping aerial photographs upon a block of material in such relationship as to produce an optical plastic image of terrain upon the block, shaping the surface of the block to coincide with the optical plastic image, and rendering portions of the surface being shaped luminous in a manner to distinguish from the optical plastic image being reproduced.

7. A method of producing a relief map which consists in projecting a pair of overlapping aerial photographs on a block of material in such rela-- tionship as to produce an optical plastic image of terrain upon the block, shaping the surface of the block to coincide with the optical plastic image, projecting upon the partially shaped surface of the block as the shaping proceeds a pattern of light rays which can be distinguished from the optical plastic image, and causing said pattern of rays to shift on said surface.

8. A method of producing a relief map which consists in projecting a pair of overlapping aerial photographs upon a block of material in such relationship as to produce an optical plastic image of terrain on the block, shaping the surface of the block to coincide with the optical plastic image, projecting upon the partially shaped surface of the block as the shaping proceeds a pattern of light rays which can be distinguished from the optical plastic image, and varying the intensity of said pattern of rays.

9. A method of producing a relief model of a three dimensional object which consists in simultaneously projecting a pair of overlapping photographs of the object taken from different camera positions on a block of material in such relationship as to produce an optical stereoscopic plastic image of the object on the block having the appearance of the object in three dimensional relief, shaping the surface of the block to coincide with the three dimensional optical plastic image and projecting upon the partially shaped surface of the block as the shaping proceeds a pattern of light rays which can be distinguished from the optical plastic image so as to enable the surfacebeing worked on to be distinguished from the image that is being reproduced.

10. A projector for use in shaping objects to correspond with an image projected thereon from another source of projection, said projector comprisinga light source arranged to project a beam at the object to be shaped and a screen interposed in said beam, said screen having small light transmitting areas so as to transmit an interrupted pattern of rays, and automatic means independent of the screen for constantly varying the intensity of the projected beam so as to cause the pattern of rays to pulsate in intensity;

11. A method of producing a relief map which consists in projecting a pair of stereoscopically related representations of the terrain to be mapped upon a block oi material in such relation as to produce an optical stereoscopic plastic image of the terrain showing the terrain in three dimensional relief, shaping the surface of the block to coincide with such three dimensional optical plastic image, and projecting upon the partially shaped surface of the block as the shaping proceeds a pattern 01' light rays which can be distinguished from the optical plastic image so as to enable the surface being worked on to be distinguished from the image that is being reproduced.

HEREWARD LESTER COOKE.