Cartographer

The Cartographer is a dedicated Forerunner facility designed to contain and provide access to the Silent Cartographer, a program featuring the complete real-time record and schematics of an installation. A central component of any installation of Forerunner construction, it is found on nearly all of their megastructures, such as the Halo Array and the shield worlds.

When activated, a Cartographer provides a real-time holographic map which can be used to navigate the massive expanse that is an installation, along with other relevant information such as pinpointing every room or location within the vast structure. The Cartographer facilities on the various Forerunner installations differ in layout and design, though the primary map rooms on the Halo installations are buried within large structures housing a network of compartments and rooms. Like the map rooms on most Forerunner facilities, the Cartographers of the Halos are protected by multiple security measures.

An artificial intelligence is able to interface with the Silent Cartographer and, for example, set navigation points on the holographic projection. A Forerunner armor's personal ancilla was able to link with the Cartographer and provide packets of information on the installation's past activities directly into the wearer's brain.

Installation 00
The Cartographer of Installation 00 was located on top of a massive spire structure, the map room itself lying in a wide open area giving a panoramic view over a massive waterfall and an ocean. Facing the desert on the other side, the Cartographer structure was protected by a large wall structure. Inside the wall was a deep chasm and an energy bridge allowing passage over it. A Terminal was located within the wall near the activation switch for the energy bridge. The interiors of the Ark's Cartographer share many architectural similarities with Alpha Halo's Cartographer shaft, although the two are considerably different in general layout.

Preceding the firing of the Halos in 100,000 BCE, the IsoDidact and 343 Guilty Spark visited the Ark's Cartographer to review the preparations for the Halo Array's deployment. When the UNSC and Sangheili forces landed on the Ark during the Battle of Installation 00 in 2552, they were prevented access to the Cartographer by its exterior wall. After the landed nearby and deployed a convoy of multiple vehicles, Commander Keyes suggested they go through the wall. The UNSC forces returned to the wall and with the assistance of 343 Guilty Spark, successfully passed through. The UNSC and the Sangheili breached the Covenant-held Cartographer with the aid of 343 Guilty Spark, and used the map facility to locate the Prophet of Truth.

Installation 04
On Installation 04, the Cartographer was located in an immense underground facility, below the middle of a large island. It was protected by a security system accessible by another underground facility on the other side of the island. These facilities were a part of the installation's larger tunnel network, with a massive shaft leading to the depths of the megastructure in between them. After disabling the security system, the main passageway to the map room was opened. For additional security measures, the Cartographer's chamber and activation panel were located on the other side of the island, and buried at least half a dozen floors below ground. The path down to the Cartographer was a labyrinth of twists and turns, making it easy to get lost.

On September 20, 2552, Spartan John-117 and two squads of marines were ordered by Captain Jacob Keyes to secure the Cartographer so that they could locate Halo's control room. The soldiers landed on a Covenant-controlled beach, which they quickly captured. The Spartan soon entered the Cartographer facility, though it had been locked from within. After disabling the lock at a nearby security station, the Spartan accessed the Cartographer, learning the location of Installation 04's control room. The AI Cortana then requested that Flight Captain Carol "Foehammer" Rawley fly John-117 below ground to the control room, though they stopped at Alpha Base.

Installation 07
The Cartographer of Installation 07, one of the original twelve Halos, was a massive structure, surpassing all of the other known Cartographer sites in scale. The map room was housed in an enormous, triangular structure protruding toward the Halo's interior out of one of the walls lining the ring's edges. The structure was shaped like a flat-topped wedge around 500 kilometers wide at its base, where it connected with the Halo's edge wall and was around 400 kilometers long from base to tip. Most of the structure's upper surface, apart from the tip, appeared largely uniform and featureless when observed from a distance. However, the wedge's tip housed a complex of vast, secondary structures, some of them dozens of kilometers high. A sleek half-arch stretched beyond the wedge's tip and an ornate lattice of cabling attached to this structure supported the main Cartographer control center, itself a complex of enormous structures, each of them the size of a small city.

The control center itself housed a series of platforms and walkways, some of them crisscrossing in many directions and facing a variety of complex display terminals monitoring the Halo's systems. Some of the walkways actually faced up- or downward in right angles and allowed passage by means of localized gravity manipulation along their surfaces.

Like several other control facilities across the ring, the Cartographer was equipped with stations allowing biological beings to interface with the Halo's systems in an emergency. During Mendicant Bias' and the Primordial's attempt to save the ring from collision with the wolf-faced planet, Chakas and a number of other humans were connected to one of these systems along with Composer-processed Forerunners, the latter supposedly necessary because the humans alone did not possess the knowledge or intellect necessary to properly interface with the ring despite having been previously imprinted with the knowledge necessary for the task.

This system used an elaborate webbing projected by a rod-like object to directly connect to each human-Forerunner pair via their skin, completely melding their neural networks with the Cartographer's controls. With the individual's consciousness now merged with the Halo's computer systems, they were flooded with the vast amounts of information and sensory input flowing through the Cartographer. The organic controllers, along with the Halo, formed a cybernetic gestalt intelligence which perceived the surrounding reality through the Halo's sensor systems and abstractions provided by the Cartographer. Numerous different event-paths and outcomes were consistently being calculated and processed while the controllers steered the ring and incessantly performed minute adjustments to its numerous systems. After the IsoDidact arrived to retake the ring, he entered the Cartographer and connected to the system with Chakas in order to see the ongoing salvage effort to the end.

Greater Ark
Like all installations involved with the Halos, the greater Ark possessed a Cartographer. During the final weeks of the Forerunner-Flood war, this facility was the site of an emergency meeting between the Forerunner military leaders before the imminent Flood attack on the greater Ark. The commanders conferred in a circle within an enormous hologram of the Ark while updates on the installation's status were provided through their ancillas. Omega Halo, the sole Halo ring present at the Ark at the time, was also projected in the hologram.

Onyx
Onyx also featured a map room, deep below the Forerunner city in what the Office of Naval Intelligence referred to as Zone 67. Onyx's map center was located below a massive domed structure in the city. Below one of seven massive landing pads in the interior was a spiraling staircase which led into a smaller chamber. The chamber housed an energy bridge, which led to the map room itself; a half-spherical chamber about 20 meters across. In the center was a holographic console which could project detailed schematics of the entire Onyx construct. The room also featured a translocation platform.

Dr. Halsey used this Cartographer structure during the Battle of Onyx, when she was trying to find the way to the portal that led to the Shield World in the core of the artificial planet.

Requiem
A localized Cartographer facility was accessed by John-117 and Cortana shortly after their arrival on Requiem during the First Battle of Requiem in 2557. From this facility, they learned the name of the shield world, although Cortana's further attempts at accessing the data within were quickly deterred by the Didact.

Trivia

 * Monitors only have built-in map systems for their own Installations, which is why UNSC forces must visit Installation 00's Cartographer, despite being accompanied by 343 Guilty Spark.
 * The Silent Cartographer is oddly named because a cartographer is someone who makes maps, not a map itself. This may imply that the Silent Cartographer is more than just a building; possibly an old Forerunner computer. This could be supported by 343 Guilty Spark stating upon arrival at its controls that "it awaits your approval", possibly meaning it was aware of the nearby Reclaimers and was expecting activation.
 * The multiplayer level Construct takes place on the Cartographer building of Installation 00.
 * It is unknown if all Forerunner structures have a Cartographer, though it is likely that all Installations possess one.
 * The Cartographers always seem to appear over a chasm.

List of appearances

 * Halo: Combat Evolved
 * Halo: The Flood
 * Halo: Ghosts of Onyx
 * Halo 3
 * Halo: Primordium
 * Halo: Combat Evolved Anniversary
 * Halo 4
 * Halo: Silentium