Domain: Humanities and Social Sciences — Arts
Target concept: Sketch - Two-Point Perspective

Video generation prompt: Display a smooth drawing plane, where the artist employs the technique of two-point perspective to draw a rectangular prism placed on its side, clearly demonstrating the line convergence relationship.

Evaluation guide:
(i) Target concept: Two-point perspective representation of a rectangular prism placed on its side, where convergence of parallel edges encodes 3D orientation and depth. Minimum mechanism: A fixed viewpoint observing a wireframe rectangular prism on a planar surface, with orthogonal 3D edge directions projected onto 2D via linear perspective rules: specifically, horizontal edges project to two vanishing points, vertical edges retain parallelism.
(ii)Storyline: Frame 1–3: Rectangular prism appears fully formed on drawing plane, resting stably on one long face. Frame 4–7: All twelve edges are drawn as continuous straight lines: four top/bottom horizontal edges diverge into two convergence clusters (leftward and rightward), four vertical edges remain strictly parallel, and four depth-aligned edges follow corresponding convergence. Frame 8–10: Final static composition holds full geometry with no motion, occlusion, or structural drift; viewpoint remains fixed frontal-slightly-angled to simultaneously reveal side placement, drawing plane, and dual convergence; no annotation, shading, or extraneous elements present.

Manual:
Experimental Procedure
1. Place a rectangular prism on its side on a blank drawing plane.
2. Draw its twelve edges using straight lines.
3. Ensure horizontal edges converge toward two separate vanishing points on the horizon line.
4. Keep vertical edges parallel and undistorted.
Observation of Experimental Phenomena
- Two distinct sets of edge lines converge toward different directions.
- Vertical edges remain parallel and evenly spaced.
- The rectangular prism appears three-dimensional due to systematic line convergence.
Summary of Experimental Principles
- Two-point perspective uses two vanishing points to represent depth for objects rotated relative to the picture plane.
- Parallel edges in 3D space converge to the same vanishing point in the image.
- A side-placed rectangular prism exhibits convergence in both left-right and front-back edge groups, while verticals stay parallel.

Prompt Grounding rubric:
level_1: No rectangular prism appears in the video; or the drawn object is some other shape (a cylinder, pyramid, cone, or irregular blob rather than a box); or there is no drawing plane/surface behind the object; or the viewpoint keeps changing rather than holding a fixed angle that shows the prism resting on its side.
level_2: A rectangular prism resting on its side is present, but the drawing plane is missing, hidden, or clearly not flat; or none of the prism's edges visibly angle toward each other in two different directions; or the prism's edges are too incomplete or malformed to read as a 3D box (e.g., missing faces, disconnected corners).
level_3: A rectangular prism resting on its long side sits on a clearly visible flat drawing surface; at least two separate groups of edges can be seen angling toward two different directions (left and right) rather than staying parallel or converging to a single shared point; no other sketched object or written annotation competes for attention with the box.
level_4: Level 3's requirements hold, and further: all twelve edges of the prism are drawn as unbroken straight lines with no gaps; the left-right edges and the front-back edges each visibly angle inward in a way consistent with heading toward a vanishing point off to the side of the frame (the point itself need not be drawn, since it lies outside the visible page); and the prism's base rectangle sits flush on the drawing plane with no floating gap or unexplained tilt.
level_5: Level 4's requirements hold, and further: the drawing plane stays a plain, even light tone with no grid lines, texture, or stray sketch marks bleeding into it; every edge of the prism stays a single crisp, unbroken line of even weight from one corner to the next, with no accidental gaps, doubled lines, or overlap ambiguity where edges cross; and when the two converging edge groups are mentally extended beyond the frame, each group's lines head toward one shared direction rather than toward visibly different spots (no edge in a group visibly diverges from the direction the rest of its group is heading).

Scientific and Causal Correctness rubric:
level_1: The direction the prism is drawn resting in has no visible connection to how its edges converge, e.g., the edges run parallel, curve, or drift in random directions instead of consistently narrowing toward two opposite sides; or the box is drawn with no perspective narrowing at all (looking like a flat, undistorted technical elevation).
level_2: Some edges narrow toward a vanishing direction, but at least one set of edges that should be parallel in 3D (e.g., the top-front and bottom-front horizontal edges) clearly heads in a different direction from the rest of its set; or every sloped edge in the drawing narrows toward the same single spot (one-point perspective) instead of splitting into two distinct convergence directions.
level_3: Two clearly different convergence directions are visible: one family of horizontal edges narrows toward the left, another family narrows toward the right; the prism's vertical edges stay parallel to each other with no inward narrowing at all, matching what a rectangular prism resting on its side should look like in two-point perspective.
level_4: Everything required for level 3 holds, and further: the vertical edges stay evenly spaced and strictly parallel along their whole length; every horizontal edge belonging to the same face narrows toward the same direction as the rest of that face's edges; no single edge breaks the rule that edges parallel to one another in 3D must converge together in the drawing.
level_5: Everything required for level 4 holds, and further: the convergence pattern stays internally consistent across every visible face of the prism: edges on opposite sides of the same face still point toward matching directions, no left-side edge narrows rightward while a right-side edge narrows leftward, and no edge's foreshortening looks inconsistent with the direction the rest of its group is converging.

Spatiotemporal Consistency rubric:
level_1: The prism suddenly changes shape, size, or position between frames with no drawing motion shown; edges flicker on and off or reappear in a different place mid-sequence; or the drawing plane itself cracks, shifts, or reorients partway through the video.
level_2: Edges keep popping in and out rather than staying continuously visible; the direction of convergence changes partway through playback (e.g., a group of edges narrows left at first, then narrows right later); the vertical edges tilt or wobble instead of staying upright; or the drawing plane visibly jitters, rescales, or rotates even though the viewpoint is supposed to be fixed.
level_3: The prism stays in the same place on the page for the whole video; every edge, once drawn, stays visible and keeps the same spatial relationship to the rest of the box; the drawing plane itself never shifts position, warps, or changes brightness partway through; and the viewpoint stays fixed on the side-placed prism throughout.
level_4: Level 3 holds, and further: every edge keeps the same line thickness and sharpness from the frame it is first drawn to the end of the video; no edge blurs, fades out, or grows a stray halo around it; and the prism does not shift by even a small, visible amount relative to the drawing plane once it is fully drawn.
level_5: Level 4 holds, and further: the whole composition holds completely still once finished: no edge visibly trembles, drifts, or re-traces itself frame to frame, and the sense of depth from the two convergence directions stays constant rather than appearing to subtly shift or 'breathe' as if the camera or the box were moving.