A cross-sectional line plot showing ground elevation along a path or transect line, with the area below the profile filled to create a terrain silhouette. Distance along the transect is plotted on the x-axis and elevation on the y-axis. This visualization is widely used in hiking and cycling route planning, civil engineering corridor design, and geomorphology to convey terrain shape and difficulty at a glance.
""" anyplot.ai
area-elevation-profile: Terrain Elevation Profile Along Transect
Library: pygal 3.1.0 | Python 3.13.13
Quality: 88/100 | Updated: 2026-06-10
"""
import os
import re
import xml.etree.ElementTree as ET
import cairosvg
import numpy as np
import pygal
from pygal.style import Style
# Theme tokens — Imprint palette
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
IMPRINT_PALETTE = ("#009E73", "#C475FD", "#4467A3", "#BD8233", "#AE3030", "#2ABCCD", "#954477", "#99B314")
# Landmark type colors — Imprint palette with semantic cues
TYPE_COLORS = {
"summit": "#AE3030", # matte red — elevation peak, highest difficulty
"pass": "#BD8233", # ochre — earthy mountain col
"hut": "#C475FD", # lavender — alpine shelter, distinctive
"valley": "#99B314", # lime — green valley floor
"town": "#4467A3", # blue — settlement / trailhead
}
# Data — Alpine hiking trail elevation profile (120 km transect)
np.random.seed(42)
distances_km = np.linspace(0, 120, 200)
base_terrain = (
800
+ 600 * np.sin(distances_km * np.pi / 40) ** 2
+ 400 * np.sin(distances_km * np.pi / 25 + 1.2) ** 2
+ 300 * np.exp(-((distances_km - 55) ** 2) / 80)
+ 500 * np.exp(-((distances_km - 85) ** 2) / 120)
- 200 * np.exp(-((distances_km - 30) ** 2) / 50)
)
noise = np.random.normal(0, 25, len(distances_km))
elevation_m = base_terrain + noise
elevation_m = np.maximum(elevation_m, 650)
landmarks = [
{"name": "Grindelwald", "km": 0, "type": "town"},
{"name": "Kleine Scheidegg", "km": 22, "type": "pass"},
{"name": "Lauterbrunnen", "km": 38, "type": "valley"},
{"name": "Mürren", "km": 55, "type": "summit"},
{"name": "Blüemlisalp Hut", "km": 72, "type": "hut"},
{"name": "Hohtürli Pass", "km": 85, "type": "pass"},
{"name": "Kandersteg", "km": 120, "type": "town"},
]
for lm in landmarks:
idx = np.argmin(np.abs(distances_km - lm["km"]))
lm["elev"] = float(elevation_m[idx])
# Title length: 80 chars → fontsize = round(66 × 67 / 80) = 55
TITLE = "Bernese Oberland Traverse · area-elevation-profile · python · pygal · anyplot.ai"
custom_style = Style(
background=PAGE_BG,
plot_background=PAGE_BG,
foreground=INK,
foreground_strong=INK,
foreground_subtle=INK_MUTED,
colors=IMPRINT_PALETTE,
font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
title_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
title_font_size=55,
label_font_size=56,
major_label_font_size=44,
value_font_size=36,
legend_font_size=44,
legend_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
label_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
major_label_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
value_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
opacity=0.70,
opacity_hover=0.85,
stroke_opacity=1.0,
stroke_opacity_hover=1.0,
tooltip_font_size=32,
tooltip_font_family="DejaVu Sans, Helvetica, Arial, sans-serif",
tooltip_border_radius=8,
)
chart = pygal.XY(
width=3200,
height=1800,
title=TITLE,
x_title="Distance (km)",
y_title="Elevation (m)",
style=custom_style,
fill=True,
show_dots=False,
stroke_style={"width": 4},
show_y_guides=True,
show_x_guides=False,
show_legend=True,
legend_at_bottom=True,
legend_box_size=30,
value_formatter=lambda x: f"{x:,.0f} m",
x_value_formatter=lambda x: f"{x:.0f} km",
interpolate="cubic",
interpolation_precision=300,
min_scale=5,
max_scale=10,
margin_bottom=90,
margin_left=90,
margin_right=120,
margin_top=50,
spacing=12,
tooltip_fancy_mode=True,
range=(550, 2100),
xrange=(0, 125),
show_minor_x_labels=False,
show_minor_y_labels=False,
truncate_legend=-1,
dynamic_print_values=True,
print_values=False,
show_x_labels=True,
show_y_labels=True,
x_labels_major_count=7,
y_labels_major_count=6,
)
# Elevation profile — first series uses Imprint position 1 (#009E73)
profile_data = [
{"value": (float(d), float(e)), "label": f"{d:.1f} km — {e:.0f} m"}
for d, e in zip(distances_km, elevation_m, strict=True)
]
chart.add("Elevation Profile", profile_data)
# Landmark markers — colored by type in SVG post-processing below
landmark_data = [
{"value": (float(lm["km"]), lm["elev"]), "label": f"{lm['name']} — {lm['elev']:.0f} m"} for lm in landmarks
]
chart.add("Landmarks", landmark_data, fill=False, show_dots=True, dots_size=20, stroke=False)
# Save interactive HTML with pygal's native tooltip support
chart.render_to_file(f"plot-{THEME}.html")
# Render SVG for annotation post-processing
svg_bytes = chart.render()
SVG_NS = "http://www.w3.org/2000/svg"
ET.register_namespace("", SVG_NS)
ET.register_namespace("xlink", "http://www.w3.org/1999/xlink")
root = ET.fromstring(svg_bytes)
parent_map = {child: parent for parent in root.iter() for child in parent}
circles = sorted(
[c for c in root.iter(f"{{{SVG_NS}}}circle") if float(c.get("r", "0")) > 3], key=lambda c: float(c.get("cx", "0"))
)
# Find plot bottom from horizontal guide paths (format: "M0.0 Y h...")
plot_bottom_y = 0
for path in root.iter(f"{{{SVG_NS}}}path"):
cls = path.get("class", "")
d_attr = path.get("d", "")
if "guide" in cls and " h" in d_attr:
m = re.match(r"M[\d.]+ ([\d.]+) h", d_attr)
if m:
plot_bottom_y = max(plot_bottom_y, float(m.group(1)))
# Stagger closely-spaced labels to avoid overlap
label_offsets = {
"Grindelwald": -44,
"Kleine Scheidegg": -44,
"Lauterbrunnen": -44,
"Mürren": -56,
"Blüemlisalp Hut": -74,
"Hohtürli Pass": -44,
"Kandersteg": -44,
}
ns = f"{{{SVG_NS}}}"
for i, circle in enumerate(circles[: len(landmarks)]):
parent_elem = parent_map.get(circle)
if parent_elem is None:
continue
cx, cy = float(circle.get("cx", "0")), float(circle.get("cy", "0"))
lm = landmarks[i]
lm_color = TYPE_COLORS.get(lm["type"], "#BD8233")
y_off = label_offsets.get(lm["name"], -44)
# Override circle fill to landmark-type color for clear visual differentiation
circle.set("fill", lm_color)
circle.set("stroke", PAGE_BG)
circle.set("stroke-width", "3")
# Text anchor by position along transect
if i == 0:
anchor, dx = "start", 14
elif i == len(landmarks) - 1:
anchor, dx = "end", -14
else:
anchor, dx = "middle", 0
# Vertical dashed marker line from dot to plot baseline
vline = ET.SubElement(parent_elem, f"{ns}line")
for attr, val in [("x1", cx), ("y1", cy), ("x2", cx), ("y2", plot_bottom_y)]:
vline.set(attr, f"{val:.1f}")
vline.set("stroke", lm_color)
vline.set("stroke-width", "2.5")
vline.set("stroke-dasharray", "8,5")
vline.set("opacity", "0.65")
# Landmark name — bold, colored by type
name_el = ET.SubElement(parent_elem, f"{ns}text")
name_el.set("x", f"{cx + dx:.1f}")
name_el.set("y", f"{cy + y_off:.1f}")
name_el.set("text-anchor", anchor)
name_el.set("font-size", "32")
name_el.set("font-family", "DejaVu Sans, Helvetica, Arial, sans-serif")
name_el.set("fill", lm_color)
name_el.set("font-weight", "bold")
name_el.text = lm["name"]
# Elevation value — muted secondary label below name
elev_el = ET.SubElement(parent_elem, f"{ns}text")
elev_el.set("x", f"{cx + dx:.1f}")
elev_el.set("y", f"{cy + y_off + 32:.1f}")
elev_el.set("text-anchor", anchor)
elev_el.set("font-size", "30")
elev_el.set("font-family", "DejaVu Sans, Helvetica, Arial, sans-serif")
elev_el.set("fill", INK_MUTED)
elev_el.text = f"{lm['elev']:.0f} m"
# Vertical exaggeration note — bottom-right, more prominent than previous version
note_el = ET.SubElement(root, f"{ns}text")
note_el.set("x", "3080")
note_el.set("y", f"{plot_bottom_y + 54:.0f}")
note_el.set("text-anchor", "end")
note_el.set("font-size", "32")
note_el.set("font-family", "DejaVu Sans, Helvetica, Arial, sans-serif")
note_el.set("fill", INK_SOFT)
note_el.set("font-style", "italic")
note_el.text = "Vertical exaggeration ~10× for terrain visibility"
# Render final PNG
cairosvg.svg2png(bytestring=ET.tostring(root, encoding="unicode").encode("utf-8"), write_to=f"plot-{THEME}.png")
Part of Terrain Elevation Profile Along Transect on anyplot.ai.