Domain: Humanities and Social Sciences — Arts
Target concept: Size Perspective (near large, far small): In painting, objects closer to the viewer are drawn larger and objects farther away are drawn smaller. This is labeled as the size perspective area, where the size of the object is inversely proportional to its distance, conforming to the laws of perspective.

Video generation prompt: Artists use perspective techniques to create their paintings on the canvas. The works include both near and distant objects, with a focus on the proportional relationship between foreground and background elements.

Evaluation guide:
(i) Target concept: Size perspective as a depictive convention in 2D visual art.
Minimum mechanism: A fixed viewpoint, planar projection surface (canvas), and co-planar ground reference enabling unambiguous inference of relative distance from vertical position and occlusion.
(ii)Storyline: Frame 1–3: Static wide shot reveals two distinct objects on shared ground plane, lower object larger, upper object smaller. Frame 4–7: Occlusion boundary remains stable: lower object consistently covers bottom portion of upper object. Frame 8–10: Horizon line stays fixed behind both objects; no motion, no repositioning, no scaling change; visual structure sustains consistent 2D pictorial logic without 3D realism cues (e.g., no parallax, no perspective grid, no volumetric lighting). Visibility is full and uninterrupted; no object enters/exits frame; all depth cues derive solely from size, position, and occlusion.

Manual:
Experimental Procedure
1. Place two identical objects (e.g., trees or columns) on a flat ground plane: one near the viewer (foreground), one far away (background).
2. Capture the scene from a fixed frontal viewpoint, mimicking a painter’s canvas.
Observation of Experimental Phenomena
The foreground object appears significantly larger and fully visible; the background object appears significantly smaller and partially occluded by the foreground object; both align to the same horizon line and ground plane.
Summary of Experimental Principles
Artists apply size perspective: object size on canvas is inversely proportional to its distance from the viewer — nearer objects are drawn larger, farther objects smaller — to simulate three-dimensional space on a two-dimensional surface.

Prompt Grounding rubric:
level_1: No large-near object and small-far object pair appears anywhere in the frame; the scene shows either a single object with no size-distance context, or multiple objects that are not staged as a foreground/background composition; nothing resembling a fixed, canvas-like framing is present.
level_2: At least one object is visible, but there is no clear larger/smaller pairing tied to vertical position: objects that do appear are similar in apparent size regardless of where they sit in frame, or the shot is not held from one fixed viewpoint (e.g., the camera pans, tilts, or the angle changes), so no canvas-style still composition is established.
level_3: Two or more objects share a single fixed-viewpoint frame, and one is noticeably larger than the other, but their placement does not yet establish a foreground/background hierarchy; for example, the larger object sits above, beside, or at the same height as the smaller one, or the two objects never touch or overlap so no near/far ordering is implied.
level_4: A clearly large, near object sits low in the frame and a clearly small, far object sits higher in the frame, both held in one fixed, canvas-like view; the large object's base overlaps the base of the small object along a single shared ground line; extra objects beyond this pair may appear without penalty as long as this primary large/small pair is unambiguous.
level_5: The large/near object stays low and the small/far object stays higher within one fixed, canvas-like view, with the large object's base overlapping the small object's base along one continuous, unbroken ground line; this pair remains the unmistakable visual anchor of the composition: the overlap edge is a single clean line rather than several crossing edges, and nothing else in the frame competes with or obscures the near/far reading of the pair, whether or not other correctly placed objects are also present.

Scientific and Causal Correctness rubric:
level_1: No size-distance correlation is visible; smaller object appears at same vertical level or lower than larger object; no occlusion or positional hierarchy; causal link between proximity and size is visually contradicted (e.g., distant object is larger than near one).
level_2: Objects differ in size but show no consistent spatial logic: e.g., larger object is higher in frame, or smaller object overlaps larger one; no occlusion, no shared ground plane, no horizon alignment; size variation appears arbitrary, not tied to position.
level_3: Larger object is lower in frame and smaller object is higher in frame; occlusion is present but inconsistent (e.g., only partial edge overlap, or reversed depth order in one region); horizon line is implied but not consistently observed across both objects; size difference is present but not reinforced by other depth cues.
level_4: Larger object is fully lower in frame and occludes the lower portion of the smaller object; smaller object is fully higher in frame and fully visible above occlusion line; both objects align to a single continuous implied ground plane extending beneath them; horizon line is consistently positioned behind both; size difference is stable and unambiguous across full duration.
level_5: Size difference is exclusively and consistently explained by spatial position: larger object is always lower and occluding; smaller object is always higher and occluded; no frame shows size reversal, misalignment, or independent scaling; occlusion boundary is clean and geometrically plausible for planar projection; no frame violates inverse proportionality between apparent size and distance from viewer.

Spatiotemporal Consistency rubric:
level_1: Objects teleport between frames; sudden appearance/disappearance; abrupt scale shift mid-video; lighting or shadow direction flips; structural break (e.g., object splits, warps, or fractures); viewpoint jumps or rotates.
level_2: One or more objects flicker or intermittently vanish; minor jitter in position or scale; shadow moves independently of object; partial occlusion appears/disappears inconsistently; horizon line wobbles or shifts vertically between frames.
level_3: All objects remain continuously visible with stable position, scale, and orientation; occlusion relationship is maintained without interruption; lighting and shadow direction remain fixed; horizon line stays at constant vertical position; no object deformation or morphing; no frame drop or temporal discontinuity.
level_4: All conditions for score 3 met; additionally, object edges remain sharp and unblurred across all frames; no inter-frame misalignment (e.g., no drifting occlusion boundary); no micro-jitter in positioning or scaling; no temporal inconsistency in depth layering (e.g., foreground never recedes, background never advances).
level_5: Zero spatiotemporal deviation: every frame maintains identical spatial configuration: same object positions, same occlusion boundaries, same horizon alignment, same lighting/shadow geometry, same aspect ratio and framing; no interpolation artifacts, no motion blur, no aliasing; all transitions between frames are pixel-perfectly continuous with no detectable temporal seam.