Domain: Humanities and Social Sciences — Arts
Target concept: Sketch - Atmospheric Perspective (clear in the foreground, blurred in the distance): The objects in the foreground are rich in detail and vibrant in color, while those in the distance are blurred and muted in color.

Video generation prompt: Demonstrate how an artist creates a landscape painting on canvas using the technique of atmospheric perspective. First, sketch the foreground objects, then the middle ground, and finally the distant mountains and sky, clearly distinguishing between the foreground and background.

Evaluation guide:
(i) Target concept: Depth perception in 2D landscape art via systematic modulation of visual properties across spatial layers.
Minimum mechanism: Human visual system interprets reduced acuity, lower contrast, and cooler/muted hues at increasing simulated distance, requiring strict correspondence between spatial position, sketching sequence, and perceptual attributes (detail, saturation, edge definition).
(ii)Storyline: [Frame 0–2] Blank canvas centered; artist hand enters frame holding dry medium; foreground sketch begins: lines are dense, high-contrast, textured, and chromatically vivid. [Frame 3–5] Middle ground sketch commences only after foreground is established: lines are sparser, lower-contrast, and desaturated relative to foreground. [Frame 6–9] Distant mountains and sky are added last: forms are simplified, edges are diffused, hues are markedly cooler and lower in saturation. Throughout: fixed frontal viewpoint; no camera motion; canvas remains rigidly positioned; all layer additions occur via contiguous hand motion without lifting or teleportation; lighting remains constant; layer zones maintain strict vertical stratification (foreground lowest, distance highest) with no spatial ambiguity.

Manual:
Experimental Procedure
1. Artist places blank canvas vertically in frame.
2. Artist sketches foreground objects (e.g., rocks, trees) with crisp lines and vivid tones.
3. Artist sketches middle ground (e.g., hills, path) with less detail and muted tones.
4. Artist sketches distant mountains and sky with soft edges and desaturated tones.
Observation of Experimental Phenomena
- Foreground objects appear sharply defined, rich in texture and color.
- Middle ground objects appear less distinct, with reduced detail and paler color.
- Distant mountains and sky appear blurred, low-contrast, and faded in hue.
Summary of Experimental Principles
Atmospheric perspective creates depth by progressively reducing detail, saturation, and edge sharpness from foreground to background.

Prompt Grounding rubric:
level_1: No landscape sketching process appears on canvas; no artist hand or drawing tool is visible; the foreground, middle-ground, and distant-mountain layers are absent; the scene bears no resemblance to a landscape being sketched in stages.
level_2: A canvas and a hand holding a drawing tool appear, but the layers are either drawn all at once with no visible sequence, or the distant mountains/sky are sketched before the foreground, or at least one of the three layers (foreground objects, middle ground, distant mountains/sky) never appears on the canvas.
level_3: All three layers (foreground objects, middle ground, and distant mountains/sky) eventually appear on the canvas, and the artist sketches them one after another, but the order is wrong (e.g., the middle ground is drawn before the foreground, or the distant mountains appear before the middle ground); no two layers are drawn at exactly the same time.
level_4: All of score 3, and the three layers are sketched in the correct order (foreground objects first, then middle ground, then distant mountains and sky), each occupying its correct vertical zone on the canvas (foreground lowest, distant layer highest) with no layer skipped or drawn out of turn, but one small inconsistency remains (e.g., a brushstroke direction that doesn't match the layer's depth, or one object slightly outside its assigned zone without changing which layer it belongs to).
level_5: The foreground objects are sketched first with dense, high-contrast lines and vivid color; the middle ground is sketched second with visibly less line density and color intensity; the distant mountains and sky are sketched third with visibly softened edges and muted color; the three layers begin strictly in that order with no overlap in their starting times, each sits in its correct vertical zone, and no object's rendering style crosses into a neighboring layer's level of detail, saturation, or edge sharpness.

Scientific and Causal Correctness rubric:
level_1: The foreground, middle ground, and distant layers show identical levels of detail, identical color saturation, and identical edge sharpness: there is no near-to-far gradient in any of these properties.
level_2: At least one layer breaks the atmospheric perspective rule: the distant mountains are as crisp and saturated as the foreground objects, or the foreground objects are blurred or washed out, or detail/saturation/edge-sharpness vary between layers with no consistent trend from near to far.
level_3: A near-to-far gradient in detail, saturation, and edge sharpness is present but incomplete: for example, the foreground and middle ground are correctly differentiated, but the distant mountains match the middle ground in sharpness rather than being softer, or the sky is oversaturated while the mountains beneath it are correctly muted, or color follows the gradient while edge sharpness does not.
level_4: All three layers show the atmospheric perspective gradient across all three properties: the foreground has the highest detail, most saturated color, and sharpest edges; the middle ground is intermediate in all three; the distant mountains and sky are lowest in detail, most muted in color, and softest in edge definition, but one small exception remains (e.g., a single distant rock retains slightly sharper edges than the rest of that layer, without breaking the overall gradient).
level_5: The foreground shows maximal detail, the most vivid color, and crisply defined edges; the middle ground shows visibly reduced detail, visibly duller color, and visibly softer edges than the foreground; the distant mountains and sky show minimal detail, the most muted color, and the softest, most diffused edges; this three-step gradient holds without exception across every object in every layer, matching the order in which the layers were sketched.

Spatiotemporal Consistency rubric:
level_1: The canvas changes position or orientation abruptly between frames; the artist's hand jumps to a new location without moving there; the drawing tool disappears and reappears without a visible lift-and-return motion; the lighting on the canvas shifts abruptly; the canvas surface's texture or sheen changes inconsistently from frame to frame.
level_2: Several noticeable breaks occur: the drawing tool lifts off the canvas and reappears in a new spot with no visible travel in between; a completed part of the foreground sketch vanishes and later reappears; the canvas rotates or changes size with no physical cause; or the shadow on the canvas changes without any corresponding change in the light source.
level_3: Small, isolated glitches occur but the sketching reads as continuous overall: one brief moment where the tool tip is not visible mid-stroke, one small shadow-edge shift on the canvas that doesn't quite match the hand's motion, or one small patch of canvas that briefly looks glossy instead of matte, but the canvas stays fixed in frame, the hand's motion is otherwise continuous, and the three layers stay in their assigned positions throughout.
level_4: The canvas stays fully in frame and stationary; the artist's hand and drawing tool move continuously with no jumps, unexplained occlusions, or disconnected repositioning; every mark on the canvas appears through a visible stroke rather than popping into existence; the lighting and shadow on the canvas stay consistent from the first frame to the last; the three layers stay in their assigned vertical zones, but one small flaw remains, such as a brief flicker in how opaque a stroke looks, or a moment of visible unsteadiness in the hand's stroke path that doesn't change where a layer ends up.
level_5: The canvas never moves and stays fully visible throughout; the artist's hand enters the frame once and sketches without lifting away, jumping, or being blocked from view; contact between the drawing tool and canvas is unbroken during each layer's sketching; every stroke visibly starts and ends within the frame; the canvas's lighting, shadow, texture, and sheen stay stable and consistent throughout; the foreground, middle-ground, and distant zones keep the same relative position and proportion on the canvas from the first frame to the last.