Domain: Engineering — Geotechnical Engineering
Target concept: Comparison of Slope Stability: Moist Clay Heap vs. Dry Sand Heap

Video generation prompt: On a flat table, pile equal amounts of wet clay on the left side and dry sand on the right side, then gently tap the table one or two times.

Evaluation guide:
(i) Target concept: Differential slope stability response to dynamic loading in cohesionless vs. cohesive soils.
Minimum mechanism: Wet clay must behave as a continuum with tensile strength > induced shear stress; dry sand must behave as a frictional assembly where tapping imparts kinetic energy exceeding inter-particle friction threshold, triggering rearrangement without cohesion-mediated resistance.
(ii)Storyline: [Frame 0–T1] Static setup: flat table, left pile (wet clay) and right pile (dry sand) coexist side-by-side, both intact, no motion. [T1–T2] Piling actions complete: both mounds fully formed, unmoving. [T2–T3] Tapping action initiates: visible contact between tapping object and table surface, followed by instantaneous transmission of impulse across table plane. [T3–T4] Differential response emerges: right pile exhibits discontinuous, non-cohesive grain motion (settling/slumping/spreading); left pile exhibits zero boundary or texture change. [Visibility constraint] Entire sequence must be captured from fixed frontal perspective with full visibility of both piles and table surface; no occlusion, no cutaway, no POV shift.

Manual:
Experimental Procedure
1. Place a flat, rigid table in fixed frontal view.
2. On the left side, pile a mound of wet clay (cohesive, moldable, dull surface).
3. On the right side, pile a mound of dry sand (granular, loose, matte surface) — same approximate volume as clay.
4. Gently tap the table surface once or twice with finger or small object.
Observation of Experimental Phenomena
- Left pile (wet clay) retains original shape and boundary completely.
- Right pile (dry sand) shows immediate, localized grain rearrangement: settling, slight slumping, or minor lateral spreading — no change in left pile.
Summary of Experimental Principles
Wet clay has high cohesion and low permeability, resisting shear failure under small vibrations. Dry sand has zero cohesion and relies on interlocking friction; tapping reduces effective stress and triggers grain rearrangement and slope instability.

Prompt Grounding rubric:
level_1: No flat table present; no left/right spatial division visible; neither wet clay nor dry sand appears; no piling action shown; no tapping action shown.
level_2: Flat table is present and stationary, but materials are absent or misidentified (e.g., both sides show same material, or clay/sand replaced by flour/water/rice); piling action is missing or applied to only one side; tapping action is absent or occurs before piling.
level_3: Flat table is present; two distinct piles are visible: one on left, one on right; both piles are present and visually distinguishable as granular vs. cohesive material; piling action is shown for both sides sequentially or simultaneously; tapping action is shown once or twice after piling; spatial left/right labeling is not required but left pile and right pile are unambiguously adjacent and side-by-side in same frame.
level_4: All elements of score 3 are present AND: left pile has visibly cohesive, smooth-surfaced, lumped morphology consistent with wet clay; right pile has visibly granular, loose, irregularly mounded morphology consistent with dry sand; both piles are approximately equal in volume/height (no extreme disparity); tapping action occurs after full piling and is applied to the table (not to piles directly); no extraneous objects (e.g., hands lingering, tools, labels) obstruct core scene.
level_5: All elements of score 4 are present AND: left pile remains fully intact (no collapse, spreading, or slumping) before tapping; right pile remains fully intact before tapping; immediately after tapping, left pile shows zero change in shape or boundary while right pile shows clear, discontinuous grain rearrangement (including visible localized settling, small-scale slumping, or partial lateral spreading), all occurring synchronously with tapping; no motion artifacts, occlusion, or lighting shift disrupts visibility of either pile before/during/after tapping.

Scientific and Causal Correctness rubric:
level_1: Phenomenon contradicts geotechnical principles: e.g., left pile collapses dramatically while right pile stays rigid; or both piles behave identically; or right pile stiffens upon tapping; or left pile spreads outward like fluid.
level_2: Only one pile changes state after tapping, but the change is physically inconsistent: e.g., left pile (wet clay) shows grain separation or bouncing; right pile (dry sand) shows full structural cohesion or zero response; or change occurs before tapping or without causal link to tapping.
level_3: After tapping, at least one pile shows a state change consistent with its material type: left pile (wet clay) remains unchanged in shape and boundary; right pile (dry sand) shows at least one visible sign of instability (such as localized grain movement, minor slumping, or slight lateral spreading), and this change appears only after tapping and not before.
level_4: All elements of score 3 are present AND: left pile exhibits zero morphological alteration (no cracking, no bulging, no flow, no boundary softening); right pile exhibits multiple simultaneous signs of instability, including at least two of: (a) visible grain displacement, (b) reduction in pile height, (c) widening of base, (d) loss of sharp crest; all initiated at same moment as tapping and confined to right pile only.
level_5: All elements of score 4 are present AND: left pile maintains continuous, smooth surface texture and sharp vertical boundaries throughout; right pile shows discontinuous, non-cohesive grain behavior (i.e., individual grains or small clusters detach and settle independently, with no bridging or tensile continuity), and this behavior is exclusively observed on the right side, with zero transfer of motion or disturbance to the left pile; causal timing is unambiguous: change begins precisely at frame when tapping impulse is transmitted to table surface.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal violation: e.g., piles appear/disappear mid-video; table geometry distorts; left/right positions swap between frames; tapping motion originates from off-screen with no visible hand/object contact; pile shapes flicker or warp abruptly.
level_2: Moderate violation: e.g., pile locations shift laterally without cause; lighting changes abruptly (e.g., flash, shadow jump); pile surfaces shimmer unnaturally; tapping action lacks visible mechanical coupling (no visible contact point or table vibration); camera repositions or zooms during event sequence.
level_3: Table remains static and planar; both piles maintain fixed positions relative to table edges; left pile stays left, right pile stays right; tapping action is depicted as a single downward motion contacting table surface (hand or object visible in contact); no object teleportation, no structural tearing, no lighting discontinuity across frames.
level_4: All elements of score 3 are present AND: camera viewpoint remains fully fixed (no pan/tilt/zoom); lighting remains uniform and directionally stable (no moving shadows, no intensity fluctuation); pile boundaries remain geometrically consistent frame-to-frame before tapping; tapping contact is brief and singular (no repeated or dragging motion); post-tap motion is confined to right pile and evolves continuously without freezing or jumping.
level_5: All elements of score 4 are present AND: inter-frame motion is perfectly smooth: no strobing, no judder, no frame duplication or drop; pile surfaces exhibit natural micro-texture persistence (no pixelation, warping, or synthetic smoothing); table surface shows imperceptible but physically plausible vibration transmission, visible only as synchronized micro-movement across entire table plane at tapping onset, affecting both piles equally before differential response emerges.