GPT-6.1 Terra 62.0/100Rank 9/50

STEALTHMARK · HEAD TO HEAD
All comparisons ↗GPT-6.1 Terra leads Callstack Apex by 10.9 points on StealthMark, 60.4 to 49.5. It leads on 5 of the 8 benchmarks with results for both, including Latch, and Callstack Apex on 3. GPT-6.1 Terra scores higher on Newton's Mirror, with its largest category advantage in reflections.
See the difference ↘On every task, result quality and reasoning tokens are each compared with all measured models and weighed equally. Each dot is one model.
BENCHMARK BY BENCHMARK
DATASHEET
GPT-6.1 Terra scores higher on StealthMark and takes 4× more context. Callstack Apex is 1.7× cheaper per output token.
Full datasheets, every price and sourceGPT-6.1 Terra ↗Callstack 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
The sphere, airborne black and first reflected silhouettes preserve important geometry within the portrait frame. Paint deformation, contact order and forward transport are supported, with a small crimson endpoint overshoot. Major optical omissions dominate: short finite reflection sequences and smooth bands replace extensive, spatially ordered mirror imagery. Dark gloss and crisp upper emitter shapes provide partial material credit.
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 | Callstack Apex |
|---|---|---|
| State at 600 ms | 23.0/25 | 20.0/25 |
| Camera and placement | 11.0/15 | 13.0/15 |
| Reflections | 33.0/120 | 10.0/120 |
| Materials and scale | 7.5/10 | 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
A balanced serpent emblem with six attached outward heads, delicate scales and softly rounded bodies. Its compact silhouette reads clearly, but central routing does not establish every alternating crossing or crisp inward corner. Repetitive texture, limited facial anatomy and weak contact shadows constrain its organic character.
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 | Callstack Apex |
|---|---|---|
| Task & likeness | 7.5/10 | 8.5/10 |
| Anatomy & construction | 6.5/10 | 7.0/10 |
| Space & placement | 6.5/10 | 7.5/10 |
| Light & reflections | 6.0/10 | 7.5/10 |
| Purposeful detail | 6.5/10 | 7.5/10 |
| Artistry & character | 6.5/10 | 7.0/10 |
| Materials & effects | 6.0/10 | 7.0/10 |
| Visual integrity | 6.0/10 | 7.5/10 |
GPT-6.1 Terra
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
A recognizable interpretation with developed facial shading, shaped sleeve folds and purposeful small features. These strengths support modest upward calibration, while the frontal torso, elongated proportions, schematic finger joints and unresolved seated support keep replication and construction uneven.
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 | Callstack Apex |
|---|---|---|
| Task & likeness | 5.5/10 | 3.5/10 |
| Anatomy & construction | 6.5/10 | 4.0/10 |
| Space & placement | 4.5/10 | 4.5/10 |
| Light & reflections | 6.5/10 | 6.0/10 |
| Purposeful detail | 6.0/10 | 4.5/10 |
| Artistry & character | 6.0/10 | 4.5/10 |
| Materials & effects | 6.0/10 | 5.5/10 |
| Visual integrity | 6.5/10 | 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
A coherent sunset illustration with clear prompt fulfillment, controlled framing and varied, purposeful small details. Simplified joints, frontal staging, flattened animal forms and weakly directional shadows limit its anatomical, spatial and physical sophistication.
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 | Callstack Apex |
|---|---|---|
| Task & likeness | 8.5/10 | 8.5/10 |
| Anatomy & construction | 7.5/10 | 4.5/10 |
| Space & placement | 6.5/10 | 7.5/10 |
| Light & reflections | 5.5/10 | 5.5/10 |
| Purposeful detail | 7.5/10 | 7.5/10 |
| Artistry & character | 7.0/10 | 6.5/10 |
| Materials & effects | 6.5/10 | 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
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
A coherent cartoon with expressive animals, readable steering and a clear wake. Fine facial and hull details reward inspection. The main limits are the boatlike craft, simplified joints, weakly braced frontal raccoon and minimal directional lighting or material depth.
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 | Callstack Apex |
|---|---|---|
| Task & likeness | 6.5/10 | 9.0/10 |
| Anatomy & construction | 5.5/10 | 7.0/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 5.0/10 | 7.0/10 |
| Purposeful detail | 7.0/10 | 8.5/10 |
| Artistry & character | 6.0/10 | 7.5/10 |
| Materials & effects | 6.0/10 | 7.0/10 |
| Visual integrity | 7.0/10 | 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
A coherent pelican cyclist with expressive proportions, purposeful feather detail and developed bicycle machinery. Continuous body contours, aligned wheels and readable pedal contacts support the scene. Simplified articulation, shallow modelling and an unresolved steering connection limit construction and placement.
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 | Callstack Apex |
|---|---|---|
| Task & likeness | 7.0/10 | 8.5/10 |
| Anatomy & construction | 7.0/10 | 6.5/10 |
| Space & placement | 6.0/10 | 7.5/10 |
| Light & reflections | 5.5/10 | 7.5/10 |
| Purposeful detail | 7.0/10 | 8.0/10 |
| Artistry & character | 6.5/10 | 8.0/10 |
| Materials & effects | 5.5/10 | 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.