Custom Themes

MapToPoster themes are defined as JSON files in the themes/ directory. Creating custom themes is simple and requires no code changes.

Theme Structure

Complete Schema

A theme JSON file contains 11 required properties:

{
  "name": "My Custom Theme",
  "description": "A brief description of the theme aesthetic",
  "bg": "#FFFFFF",
  "text": "#000000",
  "gradient_color": "#FFFFFF",
  "water": "#C0C0C0",
  "parks": "#F0F0F0",
  "road_motorway": "#0A0A0A",
  "road_primary": "#1A1A1A",
  "road_secondary": "#2A2A2A",
  "road_tertiary": "#3A3A3A",
  "road_residential": "#4A4A4A",
  "road_default": "#3A3A3A"
}

Property Reference

string

required

Display name of the theme (used in --list-themes output)

string

required

Brief description of the aesthetic and use case

hex color

required

Background color for the entire poster

hex color

required

Color for city name, country name, and coordinates text

hex color

required

Color used for top/bottom gradient fade effect. Usually matches bg for subtle fade.

hex color

required

Color for water features (rivers, lakes, ocean)

hex color

required

Color for parks and green spaces

hex color

required

Color for major highways and motorways (thickest roads)

hex color

required

Color for primary roads and main streets

hex color

required

Color for secondary roads

hex color

required

Color for tertiary roads

hex color

required

Color for residential streets (thinnest roads)

hex color

required

Fallback color for roads without specific classification

Creating a Custom Theme

Step 1: Create JSON File

Create a new .json file in the themes/ directory:

touch themes/my_theme.json

The filename (without .json) becomes the theme identifier used with --theme.

Step 2: Define Colors

Add your color palette:

themes/my_theme.json

{
  "name": "My Custom Theme",
  "description": "Dark background with vibrant green roads",
  "bg": "#1A1A1A",
  "text": "#FFFFFF",
  "gradient_color": "#1A1A1A",
  "water": "#0A2F3F",
  "parks": "#2A3A2A",
  "road_motorway": "#00FF00",
  "road_primary": "#00DD00",
  "road_secondary": "#00BB00",
  "road_tertiary": "#009900",
  "road_residential": "#007700",
  "road_default": "#009900"
}

Step 3: Use Your Theme

Reference by filename (without .json):

python create_map_poster.py -c "Paris" -C "France" -t my_theme

Design Guidelines

Road Hierarchy

Roads should follow a visual hierarchy from major to minor:

road_motorway     → Most prominent (highways, interstates)
road_primary      → Very visible (main streets)
road_secondary    → Visible (major roads)
road_tertiary     → Subtle (minor roads)
road_residential  → Most subtle (local streets)

Visual Weight Strategies:

Gradient (Recommended)
Saturation
Opacity (via Alpha)
Two-Tone

Use a smooth gradient from dark to light:

"road_motorway": "#000000",     // Darkest
"road_primary": "#2A2A2A",
"road_secondary": "#555555",
"road_tertiary": "#808080",
"road_residential": "#AAAAAA"  // Lightest

Best for: Most themes, creates natural depth

Use a single hue with varying saturation:

"road_motorway": "#FF0000",     // Full saturation
"road_primary": "#DD3333",
"road_secondary": "#BB6666",
"road_tertiary": "#AA8888",
"road_residential": "#99AAAA"  // Desaturated

Best for: Colorful themes, artistic aesthetics

Note: Hex colors don’t support alpha in the current implementation. Use lightness instead:

"road_motorway": "#0066CC",     // Full color
"road_primary": "#3385D6",      // Lighter
"road_secondary": "#66A3E0",
"road_tertiary": "#99C2EA",
"road_residential": "#CCE0F4"  // Very light

Use one color for major roads, another for minor:

"road_motorway": "#FF00FF",     // Accent color
"road_primary": "#00FFFF",      // Accent color
"road_secondary": "#00DDDD",    // Transition
"road_tertiary": "#00BBBB",     // Base color
"road_residential": "#009999"   // Base color

Best for: Bold, high-contrast themes (cyberpunk, neon)

Contrast & Readability

Background vs. Roads:

Ensure sufficient contrast between bg and road colors
Test with both dense cities (many roads) and sparse cities (few roads)

Background vs. Text:

Text must be clearly readable against bg
Aim for WCAG AA contrast ratio (4.5:1 minimum)

Water & Parks:

Should be distinguishable from bg but subtle
Usually slightly lighter or darker than bg

Color Harmony

Monochromatic

Use a single hue with varying lightness/saturation:

{
  "bg": "#F5F8FA",           // Very light blue
  "text": "#1A3A5C",         // Dark blue
  "water": "#D0E0F0",        // Light blue
  "parks": "#E0EAF2",        // Very light blue
  "road_motorway": "#1A3A5C",   // Dark blue
  "road_primary": "#2A5580",
  "road_secondary": "#4A7AA8",
  "road_tertiary": "#7AA0C8",
  "road_residential": "#A8C4E0"
}

Examples: Monochrome Blue, Ocean

Analogous

Use adjacent colors on the color wheel:

{
  "bg": "#FDF5F0",           // Warm cream
  "text": "#C45C3E",         // Orange-red
  "water": "#F0D8D0",        // Pink
  "parks": "#F8E8E0",        // Peach
  "road_motorway": "#C45C3E",   // Orange-red
  "road_primary": "#D87A5A",    // Orange
  "road_secondary": "#E8A088",  // Peach
  "road_tertiary": "#F0B8A8",   // Light peach
  "road_residential": "#F5D0C8" // Very light peach
}

Examples: Sunset, Autumn, Terracotta

Complementary

Use opposite colors on the color wheel:

{
  "bg": "#E8F0F0",           // Light cyan
  "text": "#2A5A5A",         // Teal
  "water": "#C0D8D8",        // Light teal
  "parks": "#D8E8E0",        // Pale cyan
  "road_motorway": "#B87333",   // Copper (opposite of teal)
  "road_primary": "#5A8A8A",    // Teal
  "road_secondary": "#6B9E9E",
  "road_tertiary": "#88B4B4",
  "road_residential": "#A8CCCC"
}

Examples: Copper Patina

High Contrast

Maximum contrast for dramatic effect:

{
  "bg": "#000000",           // Pure black
  "text": "#FFFFFF",         // Pure white
  "water": "#0A0A0A",        // Near black
  "parks": "#111111",        // Dark gray
  "road_motorway": "#FFFFFF",   // Pure white
  "road_primary": "#E0E0E0",
  "road_secondary": "#B0B0B0",
  "road_tertiary": "#808080",
  "road_residential": "#505050"
}

Examples: Noir, Contrast Zones

Example Themes

Example 1: Retro Gameboy

themes/gameboy.json

{
  "name": "Retro Gameboy",
  "description": "Classic Game Boy green screen aesthetic",
  "bg": "#9BBC0F",
  "text": "#0F380F",
  "gradient_color": "#9BBC0F",
  "water": "#8BAC0F",
  "parks": "#9BBC0F",
  "road_motorway": "#0F380F",
  "road_primary": "#306230",
  "road_secondary": "#0F380F",
  "road_tertiary": "#306230",
  "road_residential": "#8BAC0F",
  "road_default": "#306230"
}

Example 2: Vaporwave

themes/vaporwave.json

{
  "name": "Vaporwave",
  "description": "Retro-futuristic pink and cyan aesthetic",
  "bg": "#2A0A3F",
  "text": "#FF71CE",
  "gradient_color": "#2A0A3F",
  "water": "#01CDFE",
  "parks": "#3A1A4F",
  "road_motorway": "#FF71CE",
  "road_primary": "#05FFA1",
  "road_secondary": "#B967FF",
  "road_tertiary": "#FFFB96",
  "road_residential": "#4A2A5F",
  "road_default": "#05FFA1"
}

Example 3: Sepia Vintage

themes/sepia_vintage.json

{
  "name": "Sepia Vintage",
  "description": "Old photograph sepia tones",
  "bg": "#F4E8D8",
  "text": "#5C4A3A",
  "gradient_color": "#F4E8D8",
  "water": "#D8C8B0",
  "parks": "#E8DCC8",
  "road_motorway": "#5C4A3A",
  "road_primary": "#7A6858",
  "road_secondary": "#988878",
  "road_tertiary": "#B8A898",
  "road_residential": "#D0C0B0",
  "road_default": "#988878"
}

Example 4: Matrix

themes/matrix.json

{
  "name": "Matrix",
  "description": "Green terminal on black - hacker aesthetic",
  "bg": "#000000",
  "text": "#00FF41",
  "gradient_color": "#000000",
  "water": "#001A0A",
  "parks": "#002A0F",
  "road_motorway": "#00FF41",
  "road_primary": "#00DD38",
  "road_secondary": "#00BB2F",
  "road_tertiary": "#009926",
  "road_residential": "#00771D",
  "road_default": "#009926"
}

Example 5: Lavender Fields

themes/lavender.json

{
  "name": "Lavender Fields",
  "description": "Soft purple and lavender tones",
  "bg": "#F8F5FC",
  "text": "#6B4F8A",
  "gradient_color": "#F8F5FC",
  "water": "#D8CEEA",
  "parks": "#E8E0F4",
  "road_motorway": "#6B4F8A",
  "road_primary": "#8A6FA8",
  "road_secondary": "#A88FC0",
  "road_tertiary": "#C0AFD8",
  "road_residential": "#D8CFEA",
  "road_default": "#A88FC0"
}

Testing Your Theme

Quick Test

Test with a well-known city:

python create_map_poster.py -c "Paris" -C "France" -t my_theme -d 10000

Test Multiple City Types

Test your theme with different urban patterns:

# Test with grid pattern (Manhattan)
python create_map_poster.py -c "New York" -C "USA" -t my_theme -d 12000

# Test with organic pattern (Tokyo)
python create_map_poster.py -c "Tokyo" -C "Japan" -t my_theme -d 15000

# Test with water features (Venice)
python create_map_poster.py -c "Venice" -C "Italy" -t my_theme -d 4000

# Test with radial pattern (Paris)
python create_map_poster.py -c "Paris" -C "France" -t my_theme -d 10000

Validation Checklist

Contrast Check

Verify text is readable against background

Road Hierarchy

Ensure major roads stand out more than minor roads

Water Visibility

Check water features are distinguishable (test Venice or Amsterdam)

Park Visibility

Verify parks are visible but subtle (test Paris or London)

Dense vs. Sparse

Test with both dense cities (Tokyo) and sparse cities (suburbs)

Advanced Techniques

Gradient Fade Effect

The gradient_color creates a subtle fade at top and bottom of the poster:

// Same as background = no visible fade
"bg": "#1A1A1A",
"gradient_color": "#1A1A1A"

// Different = creates vignette effect
"bg": "#FFFFFF",
"gradient_color": "#F0F0F0"  // Slightly darker fade

Color Temperature

Warm Themes (welcoming, vintage):

Use reds, oranges, yellows, warm browns
Examples: Sunset, Autumn, Terracotta

Cool Themes (modern, calm):

Use blues, cyans, purples, cool grays
Examples: Ocean, Blueprint, Midnight Blue

Neutral Themes (professional, versatile):

Use grays, beiges, balanced tones
Examples: Noir, Warm Beige, Pastel Dream

Accessibility

Ensure your theme works for colorblind users:

Use lightness/darkness variation (not just hue)
Avoid red/green as the only differentiator
Test with colorblind simulators

Troubleshooting

Theme not appearing in --list-themes

Ensure:

File is in themes/ directory
File has .json extension
JSON is valid (use a JSON validator)
All 11 properties are present

Invalid JSON error

Common JSON mistakes:

// ❌ Trailing comma
{
  "name": "My Theme",
  "description": "Test",  // <- Remove this comma
}

// ✅ No trailing comma
{
  "name": "My Theme",
  "description": "Test"
}

// ❌ Comments not allowed
{
  "name": "My Theme",  // This is my theme
  "description": "Test"
}

// ✅ No comments in JSON
{
  "name": "My Theme",
  "description": "Test"
}

Roads not visible

Increase contrast between roads and background:

// Before (low contrast)
"bg": "#EEEEEE",
"road_motorway": "#DDDDDD"  // Too similar

// After (high contrast)
"bg": "#EEEEEE",
"road_motorway": "#333333"  // Much darker

Text not readable

Ensure sufficient contrast:

// Check contrast at https://webaim.org/resources/contrastchecker/
"bg": "#FFFFFF",
"text": "#000000"  // High contrast

// Or use complementary colors
"bg": "#1A3A5C",  // Dark blue
"text": "#E8F4FF" // Light cyan

All roads look the same

Increase the gradient range:

// Before (too similar)
"road_motorway": "#3A3A3A",
"road_primary": "#404040",
"road_residential": "#4A4A4A"

// After (wider range)
"road_motorway": "#000000",
"road_primary": "#2A2A2A",
"road_residential": "#808080"

If you create a great theme:

Test thoroughly with multiple cities
Choose a descriptive name and write clear description
Consider contributing back to the project
Share screenshots on social media

Next Steps

Theme Gallery

Browse all built-in themes for inspiration

Advanced Examples

See advanced usage patterns and techniques

Get Started

Usage

Guides

Examples

Theme Structure

Complete Schema

Property Reference

Creating a Custom Theme

Step 1: Create JSON File

Step 2: Define Colors

Step 3: Use Your Theme

Design Guidelines

Road Hierarchy

Contrast & Readability

Color Harmony

Example Themes

Example 1: Retro Gameboy

Example 2: Vaporwave

Example 3: Sepia Vintage

Example 4: Matrix

Example 5: Lavender Fields

Testing Your Theme

Quick Test

Test Multiple City Types

Validation Checklist

Advanced Techniques

Gradient Fade Effect

Color Temperature

Accessibility

Troubleshooting

Next Steps

Theme Gallery

Advanced Examples

​Theme Structure

​Complete Schema

​Property Reference

​Creating a Custom Theme

​Step 1: Create JSON File

​Step 2: Define Colors

​Step 3: Use Your Theme

​Design Guidelines

​Road Hierarchy

​Contrast & Readability

​Color Harmony

​Example Themes

​Example 1: Retro Gameboy

​Example 2: Vaporwave

​Example 3: Sepia Vintage

​Example 4: Matrix

​Example 5: Lavender Fields

​Testing Your Theme

​Quick Test

​Test Multiple City Types

​Validation Checklist

​Advanced Techniques

​Gradient Fade Effect

​Color Temperature

​Accessibility

​Troubleshooting

​Sharing Your Theme

​Next Steps

Theme Gallery

Advanced Examples

Theme Structure

Complete Schema

Property Reference

Creating a Custom Theme

Step 1: Create JSON File

Step 2: Define Colors

Step 3: Use Your Theme

Design Guidelines

Road Hierarchy

Contrast & Readability

Color Harmony

Example Themes

Example 1: Retro Gameboy

Example 2: Vaporwave

Example 3: Sepia Vintage

Example 4: Matrix

Example 5: Lavender Fields

Testing Your Theme

Quick Test

Test Multiple City Types

Validation Checklist

Advanced Techniques

Gradient Fade Effect

Color Temperature

Accessibility

Troubleshooting

Sharing Your Theme

Next Steps