Abstract: A method and apparatus for estimating vanishing points from an image, a computer program and a storage medium thereof are provided. One of the methods for detecting the vanishing points from an image includes a dividing step for dividing the image into small patches, a first detecting step for detecting each patch's local orientations, a composing step for composing lines of pencils from which at least one vanishing point is to be computed based on the local orientations detected in the first detecting step, and a computing step for computing at least one vanishing point based on the lines of pencils composed in the composing step. On the basis of the computed vanishing points, the perspective rectification on a document image can be executed accurately and quickly.

Abstract: A linear proportioner including a logarithmic mechanism to be used for transferring linear dimensions from an existing drawing, picture or actual scene to a new drawing or artist medium. An elongated assembly provides two indicators (one fixed and one variable) as reference pointers, two indicators (one fixed and one variable) for object pointers and an adjustment knob which, when rotated, moves the variable indicators synchronously and proportionally. By depressing the knob when transferring the first object dimension, the proportion ratio (transparent to the operator) is automatically set for subsequent dimension transfers.

Abstract: A drafting device creating perspective views from horizontal base lines with remote horizontal vanishing points and with a remote skyline vanishing point. The drafting device includes articulated arm assemblies on opposite sides of the board. Each arm assembly includes a lower straight edge that is pivotally connected by primary and secondary arms to a pivot arm pivotally mounted at opposed sides of the drawing board, thereby establishing an adjustable four-bar linkage that allows the straight edge to be oriented at vertically varying horizontal base lines with horizontal vertical vanishing points remote from the drawing board and variable perspective angles. In combination with ordinary drafting tools and scales, the drafter can create three dimensional objects as viewed from a horizontal base line perspective.

Abstract: A tracing an object has front and rear shells that are pivoted to each other to form a case. The rear shell defines a platform for supporting an object and the front defines a clear window pane forming a tracing plane through which the object is visible. A leg connected between the shells supports the front shell at an open position. A support movably mounted to the front shell carries a view port to view the object through the window pane and to trace an image of the object on the tracing plane.

Abstract: A portable drawing board device adapted for helping art students to draw perspective drawings, includes: (a) a generally rectangular-shaped, flat drawing surface on an upper surface of the drawing board, the drawing surface being adapted for supporting a flat drawing substrate; (b) a pair of parallel side grooves in an upper surface of the drawing board, each being parallel and adjacent to one of two opposite sides of the drawing surface, and extending the length of the drawing surface; (c) a pair of first slide adjusters adapted for sliding up and down along the side grooves; and (d) a pair of movable pivot arms, each movably attached at one end to a slide adjuster; wherein, when the first slide adjuster is in the side groove, the pivot arm extends over a portion of the drawing surface, and is adapted for assisting a user in drawing horizontal and diagonal lines on the drawing substrate.

Abstract: The invention relates to a portable and removable device for positioning and resetting a vanishing point of a perspective drawing which is to be construed on a support. The device comprises at least one stick of a given length and having opposite ends, one of these ends being provided with a transversal pin. The device further comprises a supporting member which can be removably fastened to the support. The supporting member further comprises a device for locking and positioning the stick to the member. The pin at the one end of the stick is positioned at a given distance from the member and used to locate the vanishing point. The device for positioning and locking the stick includes an adjustable abutment adapted to position the stick in a given direction. The abutment is able to remain in such an orientation after removal of the stick and the device for locking and positioning so as to reset the given direction of the stick.

Abstract: An artist's drawing device for maintaining a constant three-dimensional perspective while rendering a subject or object. The drawing device includes a first visually-defined perimeter of a planar geometric figure having a first size, a second visually-defined perimeter of a planar geometric figure having proportionate dimensions but a larger overall size than the first planar figure, and means for seeing the first and second planar geometric perimeters in a concentric spaced relation along the artist's line of sight, the smaller geometric perimeter being closer to the artist. The artist secures the device in position for viewing a subject or object therethrough such that the perimeter of the second geometric figure is eclipsed from sight by the perimeter of the first geometric figure. This fixes the artist's perspective on said subject/object in all of three dimensions, and any deviation from said fixed perspective becomes immediately apparent when the state of eclipse is lost.

Abstract: The invention consists of a focused light beam source mounted on a straight-edge, which is aligned to an off-drawing vanishing point target reference, to sketch object lines in a manner which creates depth perspective and thus maintains the three-dimensional visual character of the object to be drawn. The desired line of the object is drawn after locating and marking the reference vanishing point which will maintain that object line in visual perspective with related object lines. The straight-edge is aligned by targeting a focused light beam at the vanishing point, and the object line is drawn along the straight-edge while the light beam is striking the target marking the vanishing point. The preferred embodiment of the invention is configured with one light source, and uses reflecting mirrors which direct the light beam along the straight edge. The invention can alternately be configured with more than one light beam source, either with or without reflectors, to accomplish the same alignment function.

Abstract: A portable drafting device and learning tool for laying out perspective drawing lines to enhance the realism of standard 30 degree base line isometric drawings and other similar drawings with different base line angles. The device comprises a rectangular drawing board including a plurality of holes disposed linearly in the upper corner portions thereof for pivotally mounting a plurality of articulated arm members in functional relationship with the drawing surface. The articulated arms comprise upper arm portions which are pivotally coupled to straight-edge members, each being disposed at approximately thirty degrees to horizontal. Upper arm portions are provided with a plurality of adjustment holes for alternate placement of pivot pins, or a slot to effect vertical adjustment of the articulated arms in relation to the drawing surface. Straight-edge members may be pivoted at varying angles in relation to upper arm members to enable selective adjustment of the desired vanishing point distance.

Abstract: A drafting apparatus comprising a drawing board having at least two opposite, parallel sides, and arcuate guide means, detachably coupled to the at least two opposite, parallel sides, for guiding a straight edge along a radial path during formation of radiating perspective lines.

Abstract: A perspective drafting device including a pair of straight edges pivotally connected to a centerpiece removably fixable to the horizontal arm of a drafting machine in place of the horizontal scale. Each of the straight edges is slidable through a vanishing point guide which latter is provided with a pin on its bottom surface extending substantially orthogonally to the drafting table and projectable downwardly for pivotal seating movement within a selected one of a number of holes provided in the surface of the drafting board at the left and right margins in rows spaced vertically along the drafting board. The vertical spacing of the holes selects the particular horizon desired, whereas the horizontal spacing of the holes provides horizontal rotation of the perspective view as desired.

Abstract: A drafting table includes vertical and horizontal straight edged supports together with drive mechanisms for moving the vertical straight edge such that it will always point to a viewing point and for moving the horizontal straight edges in plural different modes. In a first mode, the two horizontal straight edges are moved such that their edges always point to respective vanishing points. In a second mode the horizontal straight edges are moved such that one continues to point to a vanishing point while the other maintains a fixed angle with respect to horizontal, and so that their edges always intersect at a point along the line of view. The drive mechanisms for the horizontal straight edge supports can be disabled, reversed or their drive ratios changed in accordance with the particular drawing being made.

Abstract: A drafting device (10) is provided for drawing parallel lines as well as true perspective lines, comprising carriage means (11) movable over a drafting surface (12) on wheel assembly means (20) and (21). A ruler (124) is located on carriage means (11) and has an unobstructed drafting edge (125) constantly co-linear with a true radial line to a chosen vanishing point. Selectively variable ratio transmission means (31), between wheel assembly means (20) and (21), permit ruler (124) to move over drafting surface (12) in a parallel or an arcuate manner about a preset vanishing point on or outside drafting surface (12). Magnet means are included for maintaining wheel assemblies (20) and (21) in frictional contact with drafting surface (12) and brake means are included to lock carriage (11) on drafting surface (12) in selected positions. Presetable stop means are provided to preset a plurality of vanishing points.

Abstract: A drafting apparatus having a linear edge with first and second wheel means associated with the edge to rotatably move the linear edge across a planar drafting surface and wherein the wheels are of differing diameter so as to have the linear edge move across an arc defined within a circle toward which the linear edge is always pointed. The center of that circle is the vanishing point as conventionally utilized with perspective drawing techniques.

Abstract: A drafting instrument (14) is provided for drawing perspective lines without physically preestablishing and marking a vanishing point. A carriage (16) and drawing blade (18) are supported on roller means (20) for movement along a drawing surface. Control means (24) adjustably pivots the roller means such that each point along the drawing blade scribes an arc about a common point as the carriage moves. The drawing blade defines substantially parallel lines in perspective radiating substantially from the common point as a vanishing point as the carriage moves.

Abstract: A drafting template having printed thereon a pattern of non-concentric elliptical portions, preferably forming complete ellipses, a vertical measuring line extending upwardly from a common point for the pattern or from a base point for the vertical measuring line, and a horizon line mounted at a scaled height above the base point and being parallel to the major axes of the elliptical portions or ellipses. The pattern is a perspective view of concentric circles or portions thereof taken at a scaled distant station point and scaled height above the plane for the circles. The horizon line is mounted at a scaled height above the base point. By selecting one or more vanishing points on the horizon (line), and drawing lines on an overlaying drafting sheet correlated to the base point between the vanishing point(s) and base point, such drawing lines intersecting the elliptical portions or ellipses, a lined grid field can be ultimately produced on the drafting sheet.

Abstract: An apparatus is provided for use in conjunction with a tiltable rectangular drafting table for producing perspective drawings within a working area centered on the table. The apparatus comprises a left side, right side and bottom holding means and an elongated drawing guide associated with each holding means. The extremities of the drawing guides which are located within the working area are pivotably joined at a juncture. Manual movement of the juncture causes simultaneous pivotal movement of the drawing guides about vanishing points in a manner to enable straight lines to be drawn for a perspective drawing.

Abstract: A drafting instrument is provided for making pictorial drawings, especially axonometric projections. The instrument is in the form of a template which is placed over the drafting surface and may be attached to a drafting machine, straight edge, T-square, or the like. The template is formed with a straight lower edge, perpendicular side edges and a pair of upper edges defining an angle corresponding to the angle of the view to be drawn, i.e. dimetric, trimetric, isometric. The template includes a vertical centerline at the junction of the two upper edges. The margins along each angled upper edge is marked with graduated markings corresponding to the particular angle of the template and parallel to the adjacent angled upper edge. The template also includes a rectangular window or slot extending parallel to the lower edge and provided with graduated markings formed along the edges thereof for use in preparing the views.

Abstract: This invention relates to a perspective drawing machine and more particularly, to a machine which will keep track of a chosen vanishing point. Two machines are disclosed; one, a mechanical machine works to .+-.22.5 degrees with an error of .+-.4.7%. The second is an electronic machine that corrects for the above error and can have a much wider range. Both machines convert instantly from the left hand vanishing point to the right hand vanishing point and then to a standard drafting machine when required.

Abstract: Apparatus by which common points in any two conventional adjacent perpendicular orthographic views of an object are utilized to produce isometric, diametric or trimetric views of the object. One form of the apparatus comprises a main plotting member shaped at least in part in the form of an isosceles triangle, and an auxiliary plotting member shaped at least in part in the form of a parallelogram, and means for orienting the auxiliary plotting member at a predetermined angle with respect to the main plotting member. The plotting members are preferably made from rigid, dimensionally stable, transparent plastic material, and lines may be scribed on the plotting members to facilitate positioning of the plotting members for location of common points in the two orthographic views and for orienting the main plotting member with respect to the tertiary axis of the two orthographic views.

Abstract: A ruler of transparent material having a first edge parallel to one of the three main projection axes of an axonometric projection drawing and a second edge at a specified angle .gamma. with one of the remaining two main projection axes. The ruler is provided on its front surface with a standard line sloping at a specified inversion angle with respect to the first edge and another standard line sloping at the inclination angle of an orthographic projection drawing with respect to the bisector of the inversion angle. An axonometric projection drawing can be made with the use of the ruler from a plan view and a front or side view drawn by orthographic projection and placed on a drawing board as arranged in the orthographic drawing.

Abstract: A device having two scales, one for vertical height and one for vanishing point distance, that permits perspective drawings to be made without the need for the actual plotting of the vanishing points; and that permits vanishing points of any distance apart to be used in any size drawing. These two scales are mathematically related and are linear in graduation with said graduation being of any convenient size or nomenclature as long as the relationship between the two scales is maintained.

Abstract: A drafting device (10) is provided for drawing parallel lines as well as true perspective lines, comprising carriage means (11) movable over a drafting surface (12) on wheel assembly means (20) and (21). A ruler (124) is located on carriage means (11) and has an unobstructed drafting edge (125) constantly co-linear with a true radial line to a chosen vanishing point. Selectively variable ratio transmission means (31), between wheel assembly means (20) and (21), permit ruler (124) to move over drafting surface (12) in a parallel or an arcuate manner about a preset vanishing point on or outside drafting surface (12). Magnet means are included for maintaining wheel assemblies (20) and (21) in frictional contact with drafting surface (12) and brake means are included to lock carriage (11) on drafting surface (12) in selected positions. Presetable stop means are provided to preset a plurality of vanishing points.