- Form Restoration Based on Prototype Deconstruction: Capturing the Core Features of “Relief Language”
The realism of true relief comes from a selective reconstruction of the prototype’s form — preserving key three-dimensional structures while compressing spatial depth to fit the sticker medium. Custom relief sticker designs must first translate the prototype into a “relief adaptation” instead of pursuing a full-detail replication.
1) Define the “Structural Hierarchy” of the Prototype: From Framework to Texture
Every prototype (e.g., human figures, plants, objects) consists of supportive structures and decorative details. For example, in floral relief, the petal’s contour curvature and overlapping layers form the structural backbone, while surface textures like veins are surface details. The design must prioritize the accurate shape of this backbone:
Contour Line “Height Difference Design”: In molding processes, key contours of the prototype should be translated into quantifiable height differences (e.g., petal edges raised 0.3mm higher than the center). These height differences should follow visual habits — such as raised midribs on leaves with slightly curled edges, avoiding uniform undulations.
Simplified Layering of Overlaps: Real-world layering (like petals) often has more than 3 layers, but stickers have limited thickness. Designers can simplify to a three-level structure: primary layer – secondary layer – shadow layer. For example, in rose relief, outer petals are the primary layer (highest), middle petals are secondary (0.15mm lower), and inner petals are represented by shadow printing rather than raised features — balancing thickness constraints with a convincing depth effect.
2) “Proportional Scaling” to Match Material Properties: Preventing Physical Distortion
Material properties limit achievable forms:
Molding processes have a minimum protrusion of ~0.05mm, while excessive heights (>2mm in PVC) risk cracking.
UV printing builds relief by ink stacking, with a single pass limited to ~0.1mm height, and sharp angles can peel off easily.
Thus, design should adapt prototype proportions:
Sharp Angle “Rounded Transitions”: Sharp features like animal claws or leaf tips should be converted to arcs with 0.1-0.3mm radius, preserving a visually sharp look while ensuring production feasibility.
Detail Density “Threshold Control”: Overdense textures (e.g., fish scales, feathers) should follow the rule of no more than 3 detail units per 2mm square to avoid visual smudging. For example, on fish scales, retain the raised contour of each scale row but omit micro-patterns, using arrangement patterns to suggest density.
- Light and Shadow Simulation Based on Visual Principles: Enhancing 3D Perception with 2D Techniques
Realism in relief depends heavily on light and shadow interplay — physical reliefs naturally create shading with real light, but stickers must simulate this through pre-designed shading to guide visual perception. This is key to sticker design compared to actual relief.
1) Gradient Design of “Light-Dark Transitions”: Simulating Natural Light Projections
Under real light, raised areas catch light (highlights), recessed areas are shaded, and mid-tones form the gradient. Stickers should replicate this using printing + embossing:
UV Relief + Screen Printing Combination: First create raised structures via molding, then apply screen printing — lighter tones on illuminated parts (e.g., petal tops), darker tones on shaded areas (like overlaps), and gradients in between.
The grayscale contrast should be within 30% (e.g., highlight at 5% gray, shadow at 35%) to avoid harsh, unnatural contrasts.
“Pseudo-Relief” Visual Trick: For ultra-thin stickers (<0.5mm), use printed halftone gradients to simulate embossing — dense light dots (~80% coverage) for highlights, sparse dark dots (~30%) for shadows, with 60% density for transitions. This leverages the human eye’s perception that dot density = brightness = height to create 3D effects without actual depth.
2) Consistency of Light Source Direction: Avoiding Visual Confusion
Real relief shading is determined by a consistent light source (e.g., top or side lighting). Inconsistent lighting in design can confuse spatial perception. It’s recommended to preset a 45° top-side light source, aligning with natural observation.
Unified Highlight Placement: The highest points (e.g., leaf midribs, noses) must have highlights consistently placed according to the preset light direction (e.g., upper right), while depressions (eye sockets, petal gaps) are shaded on the opposite side (lower left).
Shadow Length and Intensity Control: Shadows enhance depth perception and should be exaggerated yet physically plausible — the higher the relief, the longer the shadow (e.g., 0.3mm height yields ~1.5x shadow length). Shadow intensity should gradually fade with distance (e.g., 20% to 5% gray gradient).
For example, in animal reliefs, shading around joints (like limbs) should gradient outward, highlighting muscle form and reinforcing lighting logic.
