To meet the specific requirements of the buyers, the company imports the instrument from reliable vendors. The use of premium quality raw materials in the manufacturing ensures noteworthy features like high durability, easy operation, hassle free handling, low maintenance cost, rugged construction, etc. The Digital Planimeters are also loaded with features that make it a perfect match to the international paradigms in terms of quality and performance. The affordability and timely delivery has also played important role in the enhancement of the market demands of the instrument in the Indian Market. This method enables a larger cumulative measurement of area Up to 1Om2 Maximum Cumulative Measurement Value of 10m2: With the measurement by 6-digit pulse count, the N-Series Planimeter can measure a larger area by times than ordinary Planimeter. The conventional planimeter has a maximum cumulative area to measure only 0.
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The movement of the cursor in the other of the orthogonal reference coordinates causes the information in the register to be transferred to a down counter. The down counter is pulsed, by means of clock pulse signals, to a zero condition. Simultaneously the clock pulses are provided to an adder subtracter device which accumulates the pulses until the down counter obtains the zero output condition.
Description United States Patent lnventor Appl. Filed Patented Assignee John G. Peddie San Antonio, Tex. San tonio, Tex. McAuslan et a1. Primary Examiner-Robert B. Simultaneously the clock pulses ar provided to an adder subtracter device which accumulates t e pulses until the down counter obtains the zero output condition. Such mechanical integrating instruments are in common use in many civil and mechanical engineering applications.
Modern photogrammetric processing generally utilizes very rapid scanning and interpretive procedures so that any manual steps within the overall process represent serious time delays.
It is desirable that the speed of such slow steps in the determination of areas be increased to be more consistent with automated processing procedures. In addition, it is preferable that the accuracy and reliability of measurements be improved over that obtainable with purely mechanicalarrangements. Finally, it would be advantageous to generate information in the form of electrical signals which could be displayed either directly or stored for later use in a computational procedure for determining area measurements.
In well-known graphical techniques, an area to be measured may be divided into parallel strips of unit width and the total area obtained as the product of the unit width and the sum of the lengths of the strips. Various mechanical arrangements have been devised to utilize this apparently simple process, but such arrangements are limited in accuracy by the difficulty of making the strips sufficiently narrow.
By use of optical and electronic techniques, however, the measuring increments or strips" may be made quite small because the fonnation of the strips is limited only by the resolving capability of lens systems, photographic media and scanning patterns. For most measurements utilizing rectangular integration methods, the area under a given curve is found merelyby the summation of the coordinate values represented by the curve in the coordinate system. In the usual planimetric problem on a map, however, the area of interest is bounded by a closed curve spaced away from the reference axes.
Accordingly, the measuring arrangement must utilize the full coordinate values while at the same time providing for the subtraction of the incremental areas which lie outside the boundary curve. Briefly, in the present invention the boundary enclosing the specified area is traversed by a cursor element which actuates coordinate encoders for the generation of electrical signals representing incremental movements of the cursor element as it is caused to traverse the boundary.
The total area may then be displayed. Accordingly, the primary object of this invention is to pro vide apparatus capable of rapidly and accurately measuring area on graphic media such as maps, photographs and drawings.
Still another object is to provide a digital planimeter in which the measured area is indicated immediately in digital format. Yet another object of the invention is to provide a digital planimetric apparatus which can be assembled readily from standard logic elements which are commonly used in data processing equipment.
Finally, it is an object of the invention to furnish a planimetric apparatus which is fully compatible and integrable with digital computer processes and apparatus. These and other objects and novel features of the invention will become apparent in the following description and the related accompanying drawing wherein: FIG. I is a schematic showing the principal elements of the scanning portion of the digital planimeter and their interrelationship; FIG.
M is a block diagram of the timing network for the digital planimeter; FIG. A movable cursor assembly 14, with reticule I5, is arranged to slide smoothly along horizontal arm 16 and thus transmit its horizontal motion to the X-encoder 20 by means of cable 17 and pulleys 18, Horizontal arm 16 is also arranged so as to slide smoothly in the vertical direction along guides 23, 24 and to simultaneously actuate Y-encoder 25 by means of cable 28 and pulleys 29, A similar cable and associated pulleys 26, 27 are provided adjacent to guide 23 to provide a balanced and smooth operatingmotion.
In measuring area 13 the operator manually moves cursor assembly I4 carefully along the boundary line as observed in reticule The motions of cursor 14 are transmitted to X-encoder 20 and Y-encoder 25 which generate displacement signals which are utilized in the data recording or area computation circuitry to be described in detail hereinafter. Thus, if the planimeter index or cursor 14 is placed on the boundary curve at, say, any Y-line, the x-coordinate value may be determined.
As cursor l4 traverses the boundary curve it may be assumed that a halt is made at each Y-line, representing an incremental command step, and that the associated x-coordinate value is determined during the halt. In effect, the x-coordinate readings taken at the two boundary intercept points xl and x, will furnish the incremental distance x x which when multiplied by the y-increment step, or Ay, will furnish the small incremental area, y XV-2 I Since the y-increments or command steps are all equal, it can be seen that the order in which x-coordinate values are determined is immaterial in the final summation, provided the boundary curve is traversed carefully and without overlap.
Further, it is also evident that the absolute values of x,,x Thus, if y is chosen as the command coordinate, which is to determine the measuring increment, then the x-coordinate value can be defined as positive when y is moving away from the x-axis, and negative when y moves toward the x-axis.
More simply, x can be considered positive when the y command value, as defined by the usual x-y coor dinate system, is increasing, and x must then be recorded as negative when the y command is decreasing in value. The proper sign for each x-coordinate value may be determined readily by noting the direction in which y-command has changed since the last halt.
The total area is then determined by algebraically summing all the values of the x-coordinate and multiplying this sum by the incremental value of y. The above-outlined calculations may be automatically computed by the arrangement of apparatus shown in FIG.
Various means, which will be described later, may be arranged to supply up-down signals corresponding to increasing or decreasing values of the x-coordinate. The total accumulated value may be shown on display This indicated x summation multiplied by the value of the y increment represents the measurement of the desired area. The simplified representation of FIG.
X-encoder and quadrature converter 38 furnish coordinate pulses and sign control signals to the X to register 70 which includes stages 71, 72, 73, Stages are interconnected respectively by carry logic circuits such that X-register 70 operates as an updown counter in response to the input signals provided by quadrature converter Binary-coded-decimal format is preferred for compatibility with associated equipment and analysis.
Suitable up-down signals, actually representing the sense of either forward or reverse rotation of X-encoder 20, are derived by phase comparison means in quadrature converter Although various types of up-down counters may be adapted for use in X-register 70, the novel three-input counter disclosed in my previous US. The use of four stages 71, 72, 73 and 74 in X-register 70 is, of course, by way of illustration and additional units may be included to extend the range and accuracy.
Up-down counter stages comprising x-register 70 provide. In order to automatically compute the area, it is necessary that the instantaneous incremental xcoordinate values be transferred or read out at the sampling or y-increment instants, as determined by the output from Y-encoder Using the previously described graphical illustration, this Y-encoder transfer signal or command occurs at the instant corresponding to the crossing of a Y-line on the graph.
Down counter 80 the operation of which is more fully described below, comprising stages 8l84, is actuated from timing network in response to a command signal from Y- encoder and quadrature converter 86, so as to acquire by transfer the x-coordinate values from X-register 70 at the proper sampling instants.
This transfer of information is effectively provided to accumulator 88 by utilizing controlled clock signals, from clock I30, to pulse down counter down from the stored xcoordinate value to a zero count, which condition is recognized by zero recognition NAND gate Simultaneously with the down counting of down counter 80, clock pulses are transmitted to accumulator 88 to effect the algebraic summation with the previously accumulated x count.
Accumulator 88 comprises another group of counter stages which may be interconnected as shown in my previously mentioned US. The operation of the apparatus in FIG. The current x-coordinate pulses from X-encoder 20 are converted into digital form by quadrature converter 38 and temporarily stored in X-register When the y increment or command signal is generated by Y-encoder 25 y has crossed a line" , timing network is actuated so as to disable, via clock control NAND gate , pulses from clock I Simultaneously, the timing network furnishes a transfer command to down counter 80 to accept the count reading from X-register When the X-register count is present in down counter 80, clock I30 starts sending pulses into down counter 80 via clock control gate under control of timing network Simultaneously, clock pulses are sent into accumulator 88 for addition or subtraction as controlled by the up or down" signal from the y quadrature converter 86 and accumulate with the previous count retained therein.
The zero output condition of down counter 80 is sensed by zero recognition NAND gate85 which then stops the clock pulses from clock I30 by disabling clock control gate The clock pulses into accumulator 88 are terminated and the accumulated total count is shown on display 37 as the x-coordinate summation.
The accumulated and updated total in accumulator 88 which is displayed by display 37 is the current total area traversed by cursor l4 since the y incremental constant is conveniently selected as unity. With respect to functioning of down counter 80, it should be noted that the counter stages 8l84 are held permanently in a down mode by a logical I applied to the down input, while the up input is permanently connected to logical 0 as represented by the circuit ground.
This control configuration is necessitated by the fact that down counter 80 is preferably constructed in accordance with the Reversible Binary Coded Decimal Synchronous Counter Circuits" as described in my aforementioned pending US.
Those skilled in the art will recognize that more conventional down counter circuits can be substituted for that shown in FIG. The pulse signals from X quadra ture converter 38 FIG. The output of NAND gate 79 is then applied to the input of carry logic circuit 76 along with the carry output from counter stage Carry logic circuits 76 and 77 are similar to carry logic circuit 75 with the exception that for carry logic circuits 76 and 77 the input shown in FIG.
An embodiment of the circuitry comprising X quadrature converter 38 is shown in FIG. The operation of the converter will be more easily understood with reference to the signal waveform shown in FIG 4c.
Quadrature converter 38 is comprised entirely of NAND gate circuit elements, inverter circuits using a NAND gate circuit configuration, and capacitor-resistor networks which serve to provide the necessary differentiated pulses. The NAND circuit configuration is for convenience only, since most of the logic elements of the digital planimeter are comprised of such NAND gate elements.
Those skilled in the art will recognize that other logic circuitry may also be substituted for that shown in FIG. The two series of output signals from Xencoder are out of phase by 90 as indicated by signal waveforms A and B in FIG. Output signals A and B are provided to inverter gates 39 and 47, respectively, which are NAND gate elements having their inputs paralleled to perfonn an inverter function.
The inverted outputs A and B are respectively applied to capacitor-resistor netwgks 41, 42 and 52, 53 to form the indicated output A and B". These signals are respectively inverted by inverter circuits 43 and 54 to provide signals A" and B" which are shown in FIG. Simultaneously, the respective outputs from inverter circuits 39, 47 are provided through inverter circuits 40, 48 respectively, and then to capacitor-resistor networks 0 44, and 49, 50, respectively,- to provide the indicated outputs A and B.
The signals A and B are then each inverted, respectively, by inverte circuits 46 and 51 to form the indicated outputs A: a r id B which are also shown in FIG. These outputs are then combined accordingto the logic equations at the bottom of FIG. The pulse output from the X-con verter, which is indicative of the movement of the cursor in the X-direction, is formed through NAND gate 65 and inverter 66 in accordance with the logical equation appearing at the bottom of FIG.
The UP, DOWN and pulse output signals of the X-converter provide the necessary control signals to properly operate register 70 so as to provide therein an instantaneous accumulation of information which represents the movement of cursor 14 in the X-direction.
The Y-encoder circuitry is similar to that of the X-encoder circuitry just described except that the pulse output signal from the Y-converter is altered such that each pulse output represents a traversal of one unit of the cursor in the y coordinate direction. Thus, the Y quadrature converter circuitry 45 may preferably comprise an oscillator having a sufficiently high oscillation frequency to provide the necessary accuracy of measurement.
For example, the oscillator frequency 5 of clock may be five megacycles. The oscillator is synchronized with the output pulse from quadrature converter 86 to form the clock pulses which are provided toNOR along with the pulse output from Y quadrature converter As shownin FIG. The NORd pulses are also provided to the clock inputs of flip-flops and Flip-flops I23 and are interconnected to provide the indicated signal at D which serves to control the gating of inverted clock pulses B, in conjunction with zero detection signal E which is obtained from zero recognition circuit from the zero output condition of counter stages in down counter The inverted I3 clock pulses, along with signal D and zero detection signal E, are provided to the input of NAND gate and the output of NAND gate is inverted by inverter to provide the indicated control clock output signal G.
This latter signal is applied, as shown in FIG.
Top-bottom max. This method enables a larger cumulative measurement of area Up to 1Om2 Maximum cumulative measurement value of 10m2:With the measurement by 6-digit pulse count, the N-Series Planimeter can measure a larger area by times than ordinary Planimeter. The conventional planimeter has a maximum cumulative area to measure only 0. If measurement value shows over 0. This requires to register the numbers of how many times these resettings are occurred. Easy conversion function of unit and scale:KPN and KPN can convert easily the measured area value into a new area value in a newly desired unit and with a newly desired scale value.
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