GPT-6.1 Terra Low 36.1/100Rank 26/51

STEALTHMARK · HEAD TO HEAD
All comparisons ↗Callstack Apex leads GPT-6.1 Terra Low by 8.2 points on StealthMark, 49.5 to 41.3. It leads on 5 of the 8 benchmarks with results for both and GPT-6.1 Terra Low on 3, including Latch. Pixel Canary scores higher on Ground Truth.
See the difference ↘BENCHMARK BY BENCHMARK
DATASHEET
Full datasheets, every price and sourceCallstack Apex ↗
Anticipating threats and planning ahead. Collect coins while avoiding ghosts. Ghosts move before the player each turn, and collisions cost a life. 3 levels in sequence, up to 66 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.

Cooperative planning and learning from experience. Coordinate two robots to push numbered cores onto matching sockets. Pressure plates hold doors open; moving either robot uses one turn. 5 levels in sequence, up to 152 turns in total. Earlier moves and outcomes carry forward, testing learning across levels.


Physics, perspective and recursive reflections, tested together. Explore the test ↗


GPT-6.1 Terra Low
Deformed colored paint and a separate airborne black body establish readable interaction history. Cyan has travelled too far, framing differs substantially, and the mirror system supplies only elementary bands and oval copies. Missing recursive geometry, nested spherical imagery and emitter mapping remain the dominant weaknesses.
Callstack Apex
The principal sphere placement and paint contact sequence are supported. Isolated sphere and panel images provide limited optical structure, but missing lateral chains and side-floor continuations prevent a coherent repeating mirror room. The main and reflected spheres lack ordered curved nested imagery, while sparse planar emitter images and incomplete spherical emitter mapping leave most of the reflection system unsupported.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| State at 600 ms | 22.0/25 | 20.0/25 |
| Camera and placement | 4.0/15 | 13.0/15 |
| Reflections | 10.0/120 | 10.0/120 |
| Materials and scale | 6.0/10 | 7.0/10 |
| Floor-damage reward | 0.0/10 | 0.0/10 |
A spinning metal sphere and paint in a mirrored room test physical reasoning, perspective and consistency across repeated reflections.
Visual construction and creative interpretation.


GPT-6.1 Terra Low
Six attached outward-facing heads, delicate scales and soft ivory shading establish an orderly decorative motif. Separate paddle-shaped bodies replace the required interlocking loops and leave no enclosed central hexagon. Surface detail provides interest, but repeated simple forms, schematic faces and limited anatomical modeling constrain the result.
Callstack Apex
The cheerful yellow bird, cream eyes, orange features and miniature teal console closely match the brief. Clean block edges, restrained colors and soft shadows create an appealing composition. The body reads more like a gridded disc than a fully cubic sphere, and the outlined left wing has limited volume. The right wing reaches the cyan block, though its grip is ambiguous.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| Task & likeness | 4.0/10 | 8.5/10 |
| Anatomy & construction | 3.5/10 | 7.0/10 |
| Space & placement | 4.5/10 | 7.5/10 |
| Light & reflections | 5.5/10 | 7.5/10 |
| Purposeful detail | 5.5/10 | 7.5/10 |
| Artistry & character | 5.0/10 | 7.0/10 |
| Materials & effects | 5.5/10 | 7.0/10 |
| Visual integrity | 4.0/10 | 7.5/10 |
GPT-6.1 Terra Low
A pale serpent woven into an interlocking knot tests connected anatomy, repeated structure and readable overlaps. Organic surface detail must work with the overall geometry.
Callstack Apex
A rounded bird built from small cubes explores a miniature machine. The scene tests block construction, expressive proportions, contact and soft lighting.
Precise visual recall and portrait reconstruction.


GPT-6.1 Terra Low
A recognizable, coherent portrait with purposeful facial detail, warm local volume and layered scenery. The frontal pose, enlarged face, merged hands and shallow clothing construction substantially limit replication and drawing skill. The visible successes support retaining the current assessment.
Callstack Apex
The framed portrait recalls Mona Lisa through dark hair, folded arms and a hazy landscape. Replication is limited by wide, staring eyes, an elongated neck and a downturned mouth. The overlapping hands lack convincing finger and wrist construction. Soft tonal shading suggests volume, but pervasive blur obscures clothing, landscape and anatomical detail.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| Task & likeness | 5.0/10 | 3.5/10 |
| Anatomy & construction | 4.5/10 | 4.0/10 |
| Space & placement | 5.0/10 | 4.5/10 |
| Light & reflections | 6.0/10 | 6.0/10 |
| Purposeful detail | 5.0/10 | 4.5/10 |
| Artistry & character | 5.5/10 | 4.5/10 |
| Materials & effects | 5.0/10 | 5.5/10 |
| Visual integrity | 6.0/10 | 5.5/10 |
An SVG interpretation of the Mona Lisa tests facial likeness, anatomy and the composition of a familiar portrait.
Creativity, perspective and visual beauty.


GPT-6.1 Terra Low
A coherent sunset scene demonstrates the beach, animals, birds and reflections. Flowing silhouettes, warm color transitions and intact attachments are its strongest properties. Simplified anatomy, the turtle's elevated viewing angle and symbolic surface effects constrain drawing complexity and physical depth.
Callstack Apex
A cohesive sunset beach illustration with lively wildlife, playful accents, and an appealing warm-to-purple palette. Palm framing and the aligned sun reflection organize the scene, while connected silhouettes keep the activities readable. Schematic joints, ambiguous dolphin junctions, loosely matched reflections, and repetitive surface marks limit construction, lighting coherence, and material depth.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| Task & likeness | 8.0/10 | 8.5/10 |
| Anatomy & construction | 5.5/10 | 4.5/10 |
| Space & placement | 5.5/10 | 7.5/10 |
| Light & reflections | 6.5/10 | 5.5/10 |
| Purposeful detail | 6.0/10 | 7.5/10 |
| Artistry & character | 5.0/10 | 6.5/10 |
| Materials & effects | 5.5/10 | 7.0/10 |
| Visual integrity | 7.5/10 | 4.0/10 |
A busy shoreline at sunset tests scene composition, animal forms and the relationship between light and water reflections.
Physical reasoning, light and visual reconstruction.


GPT-6.1 Terra Low
This benchmark has not been assessed yet.
Callstack Apex
This benchmark has not been assessed yet.
A plank, computer mouse and blueberry in a steel room test physical stability, spatial relationships, materials and lighting.
Scene composition and interacting subjects.


GPT-6.1 Terra Low
Recognizable animals, a coherent craft and sweeping wake make an appealing cartoon. Basic limb construction, weakly demonstrated raccoon seating and limited shared perspective constrain the scene. Small identifying details work well, while lighting and materials remain broadly graphic.
Callstack Apex
The raccoon clearly rides the dog's back, and the dog's paws reach the jet ski controls. Expressive faces, a sweeping tail and a strong sunset composition give the illustration character. Limbs remain connected, but the dog's foreleg joints and vehicle seating are loosely constructed. Angular splashes convey speed more successfully than convincing water displacement; lighting and reflections remain decorative.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| Task & likeness | 6.5/10 | 9.0/10 |
| Anatomy & construction | 5.0/10 | 7.0/10 |
| Space & placement | 5.5/10 | 7.5/10 |
| Light & reflections | 4.5/10 | 7.0/10 |
| Purposeful detail | 6.0/10 | 8.5/10 |
| Artistry & character | 5.0/10 | 7.5/10 |
| Materials & effects | 5.0/10 | 7.0/10 |
| Visual integrity | 6.0/10 | 8.0/10 |
A jet-ski scene pairs a canine driver with a raccoon passenger. It tests the placement and contact of interacting subjects, along with vehicle construction.
Subject construction and spatial relationships.

GPT-6.1 Terra Low
A coherent coastal illustration with a distinctive pelican, controlled contours and clearly organised bicycle wheels. Visible saddle support and shaped neck and wing contours earn credit beyond basic geometric construction. Rubbery legs, unresolved pedal contacts and absent steering contact limit the riding action. Lighting and materials remain restrained and spatially shallow.
Callstack Apex
An appealing cartoon with a distinctive pelican, expressive eye, warm bill and carefully drawn bicycle wheels. The wing reaches the handlebar, but the feet do not clearly engage the pedals, weakening the riding mechanics. Layered hills create depth; limited ground shadows weaken contact. Clean curves and purposeful feather details give the illustration polish.
| Category | GPT-6.1 Terra Low | Callstack Apex |
|---|---|---|
| Task & likeness | 7.0/10 | 8.5/10 |
| Anatomy & construction | 5.5/10 | 6.5/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 5.5/10 | 7.5/10 |
| Purposeful detail | 6.5/10 | 8.0/10 |
| Artistry & character | 6.0/10 | 8.0/10 |
| Materials & effects | 6.0/10 | 7.5/10 |
| Visual integrity | 6.0/10 | 8.0/10 |
A cycling pelican tests anatomy, riding posture and contact between the bird and the bicycle.