# GRLE Schema

The GRLE Schema defines technical specifications for Farming Simulator's internal image layers and rendering parameters. This configuration controls how Maps4FS generates various game-critical information layers that manage gameplay mechanics, collision detection, and visual effects.

## **⚠️ Farming Simulator 25**

## File Location

The GRLE schema is located in your **Data Directory**:

```
📁 Data Directory/
└── 📂 templates/
    └── 📄 fs25-grle-schema.json  ← GRLE layer definitions
```

## **⚠️ Customization Policy: Customize With Caution**

### **Customization Risks**

* **GRLE schema can be customized**, but only if you understand FS/GE layer requirements
* **Invalid values can break generation** or produce unusable maps
* **Not every layer should be changed** - many are engine-sensitive technical layers
* **Always back up** your schema before editing

### **When Customization Makes Sense**

* **Template-specific workflows** (for example custom multifruit templates)
* **Advanced compatibility adjustments** required by a specific map template
* **Controlled experiments** where you can validate results in Giants Editor

### **Extended Foliage Example (Supported Use Case)**

* If your template uses **extended foliage types**, `densityMap_fruits.png` may need `data_type: "uint16"`
* In this mode, Maps4FS can update `map.i3d` foliage layer channel settings to match extended foliage usage
* This enables values beyond uint8 limits for foliage states/types
* Use this only with templates that are prepared for extended foliage

## Schema Purpose

The GRLE schema serves as **Maps4FS internal configuration** for generating Farming Simulator-compatible layer files:

### **Information Layers Defined**

* **Environment data** - Environmental conditions and effects
* **Farmland boundaries** - Property and ownership definitions
* **Field types** - Crop compatibility and field classifications
* **Indoor masks** - Building and structure interior detection
* **Lime levels** - Soil acidity and treatment requirements
* **Navigation collision** - AI pathfinding and movement restrictions
* **Placement collision** - Object placement validation and constraints
* **And many more technical layers...**

## Schema Structure

Each layer definition includes precise technical parameters:

```json
{
  "name": "infoLayer_fieldType.png",
  "height_multiplier": 2.0,
  "width_multiplier": 2.0,
  "channels": 1,
  "data_type": "uint8"
}
```

### **Technical Parameters**

* **`name`**: Output filename for the generated layer
* **`height_multiplier`**: Vertical resolution scaling factor
* **`width_multiplier`**: Horizontal resolution scaling factor
* **`channels`**: Color channel count (1=grayscale, 3=RGB, 4=RGBA)
* **`data_type`**: Binary data format specification

### **Multiplier Impact**

* **2.0**: Double resolution (higher detail, larger files)
* **1.0**: Standard resolution (balanced quality/size)
* **0.5**: Half resolution (lower detail, smaller files)
* **0.25**: Quarter resolution (minimal detail, compact files)

## Layer Categories

### **Gameplay Mechanics**

* `infoLayer_farmlands.png` - Property and ownership boundaries
* `infoLayer_fieldType.png` - Crop planting restrictions and field types
* `infoLayer_limeLevel.png` - Soil pH and treatment requirements

### **Physics & Collision**

* `infoLayer_navigationCollision.png` - AI movement pathfinding data
* `infoLayer_placementCollision.png` - Object placement validation
* `infoLayer_indoorMask.png` - Interior space detection

### **Environmental Systems**

* `infoLayer_environment.png` - Weather and environmental effects
* Various seasonal and weather-related data layers

### **Technical Rendering**

* Multiple specialized layers for graphics engine optimization
* Internal FS25 rendering pipeline requirements
* Performance optimization parameters

## Integration with Maps4FS

### **Automatic Processing**

Maps4FS uses GRLE schema to:

* **Generate required layers** automatically during map creation
* **Apply correct resolutions** based on multiplier settings
* **Ensure compatibility** with FS25 engine requirements
* **Optimize file sizes** while maintaining quality standards

### **No User Intervention Required**

* **Transparent by default** - most users don't need to touch GRLE schema
* **Automatic optimization** - Maps4FS handles standard cases
* **Advanced mode available** - expert users can customize with caution

## Why This Schema Exists

### **Evolution**

* **New rendering engine** requires precise layer specifications
* **Enhanced gameplay features** need additional data layers
* **Performance optimization** demands exact technical parameters
* **Compatibility assurance** prevents game crashes and errors

### **Maps4FS Adaptation**

* **Engine compliance** - Ensures generated maps work with FS25
* **Quality consistency** - Maintains standard across all generated maps
* **Future-proofing** - Allows adaptation to FS25 updates and changes

## Technical Background

### **GRLE Format**

* **Proprietary format** used by Giants Engine (FS25's game engine)
* **Optimized compression** for game performance
* **Multi-channel support** for complex data storage
* **Resolution flexibility** for different detail requirements

### **Generation Pipeline**

1. **Maps4FS processes** terrain and feature data
2. **Schema defines** output specifications for each layer
3. **Engine converts** data to GRLE format with correct parameters
4. **FS25 loads** generated layers for gameplay functionality

## Best Practices

### **Safe Customization Approach**

* **Start from defaults** and modify only what you must
* **Change one field at a time** and test generation after each change
* **Validate output in Giants Editor** before using results in production
* **Keep schema backups** so rollback is immediate
* **Focus on inputs first** (DEM/OSM/textures), then adjust schema only when needed

### **Troubleshooting Strategy**

* **GRLE problems**: Check input data (DEM, OSM) for corruption
* **Generation failures**: Verify template integrity and file permissions
* **Compatibility issues**: Ensure using the latest Maps4FS version

## ⚠️ Support Policy

### **Support Scope for Custom Configurations**

* **Default schema path** has full support
* **Custom schema path** is supported on a best-effort basis
* **Template-specific customizations** may require user-side validation and iteration
* **If issues occur**, first retry with default schema to isolate the problem

### **Recommended Approach**

* **Use defaults first** for reliability
* **Customize with caution** only for clear use cases (e.g. extended foliage uint16)
* **Document your changes** so they can be reproduced and reviewed
* **Report bugs** with both default and customized behavior details


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