Day 31: Chart Creation & Export – Masterpiece Edition | River Warrior

🗺️ DAY 31: CHART CREATION & EXPORT

⏱️ Estimated Reading Time: 13 Minutes | 🎓 Level: Professional Hydrographer

From Grid to Professional Chart – Contours, Colour Maps, and Industry Formats

Instructor: Engr. Rokib Hossain | River Warrior Academy

🏠 Course Homepage

📖 Table of Contents (Serialised)

Why Professional Chart Creation Matters
Essential Chart Elements (IHO S‑44)
Contour Generation & Interval Selection
Interactive Contour Interval Calculator
Colour Ramps & Hillshade
Export Formats: GeoTIFF, BAG, S‑57, PDF, XYZ
Step‑by‑Step Chart Creation Workflow
Chart Creation & Export Checklist
Resources & Software Tools
Frequently Asked Questions
Action Items & Next Steps

1. Why Professional Chart Creation Matters

The final deliverable of any hydrographic survey is a chart or map that communicates depth information clearly to mariners, engineers, or environmental scientists. A professionally created chart must:

Be visually clear (colours, contours, labels).
Include all metadata (survey date, datum, projection, scale).
Comply with IHO S‑44 standards for navigational charts.
Be exportable to both raster (PDF, PNG) and vector (GeoTIFF, BAG, S‑57) formats.

A poor chart can hide hazards or confuse users – undermining the entire survey effort.

🧠 Golden Rule: Always include a legend, scale bar, north arrow, and datum statement. Never assume the user knows the projection.

🌊 River Warrior Pro-Tip: Jamuna Navigation Chart Lesson

During a Jamuna River port project, we delivered a beautiful colour‑shaded chart but forgot to label the contour intervals. The port engineer couldn't determine the 5‑m contour accurately. Now we always embed a contour interval table directly on the chart layout.

2. Essential Chart Elements (IHO S‑44)

.htmlProjection & datum那样e.g., UTM zone 45N, WGS84..htmlVertical datum那样Chart Datum (LAT) and tide reduction reference..htmlColour bar那样Depth scale with colour gradient..htmlContour lines那样Isobaths at regular intervals..htmlScale bar & north arrow那样For distance and orientation..htmlSource note & disclaimer那样Hydrographic office / surveyor signature.

Element	Description
Title block那样Survey area name, date, scale.

Essential elements of a hydrographic chart layout.

3. Contour Generation & Interval Selection

Contours (isobaths) connect points of equal depth. They are derived from the bathymetric grid. Choosing the right contour interval depends on the depth range and intended use:

Port/harbour charts (0‑10 m): 0.5 m or 1 m intervals.
Coastal/navigation (10‑30 m): 1‑2 m intervals.
Offshore/deep (>30 m): 5‑10 m intervals.

Most software (Qimera, CARIS, Hypack) can generate contours automatically from a grid. Always smooth contours slightly to remove jaggedness caused by grid noise.

📏 Contour Interval Assistant

Enter depth range to get recommended contour interval:

Min depth (m): Max depth (m):

Recommended interval: 1.0 m

For IHO Order 1a, use intervals ≤ 0.5 m in shallow areas.

4. Colour Ramps & Hillshade

Colour ramps (colour maps) help users quickly identify depth zones. Common conventions:

Shallow (0‑5 m): Red / orange (danger).
Intermediate (5‑15 m): Green / yellow.
Deep (>15 m): Blue / dark blue.

Add a hillshade layer (illuminated relief) to highlight seabed topography. Hillshade combined with a semi‑transparent colour map creates a professional appearance.

Example colour ramp for bathymetric charts.

5. Export Formats: GeoTIFF, BAG, S‑57, PDF, XYZ

Different users need different formats:

.htmlBAG (Bathymetry Attributed Grid)那样IHO standard for bathymetry那样Contains uncertainty, metadata那样Limited software support.htmlS‑57 / S‑101 (ENC)那样Electronic Navigational Charts那样Official IHO standard那样Complex creation workflow.htmlPDF (georeferenced)那样Reporting, printing那样Easy to share, print那样No 3D analysis.htmlXYZ (ASCII)那样Custom analysis, volume calc那样Simple, universal那样Large file, no metadata

Format	Use	Pros	Cons
GeoTIFF (raster)那样Backdrop for GIS, web maps那样Georeferenced, universal那样No 3D, large file size

✅ Recommendation: Deliver a GeoTIFF for GIS users, a PDF for clients, and an XYZ for engineers who need volume calculations.

6. Step‑by‑Step Chart Creation Workflow

1️⃣ Load cleaned grid (e.g., CUBE surface).

2️⃣ Generate contours (choose interval).

3️⃣ Apply colour ramp and hillshade.

4️⃣ Add layout elements (north arrow, scale bar, title).

5️⃣ Export to required formats.

💡 Pro tip: In Qimera, use “Chart Composer” to design a custom layout. In CARIS, use “Map Composer”. Always preview at final paper size.

7. Chart Creation & Export Checklist

Final grid loaded with correct projection and datum.
Contours generated with appropriate interval.
Colour ramp applied (follows safety conventions).
Hillshade added and blended appropriately.
Layout elements: title, legend, scale bar, north arrow.
Metadata block: survey date, vessel, datum, tide reduction.
Georeferenced PDF created (printable).
GeoTIFF exported with world file (.tfw).
XYZ file exported (if requested).
BAG or S‑57 created for official archives (if required).

Click items to track progress (saved in browser).

8. Resources & Software Tools

.htmlCARIS HIPS & S‑57 Composer那样ENC creation, S‑57 export那样teledynecaris.com.htmlHypack Charting那样Profile, cross‑section, volume那样hypack.com.htmlQGIS (open source)那样Contour from grid, hillshade, print composer那样qgis.org

Software	Charting Features	Link
QPS Qimera那样Chart composer, contour, GeoTIFF, BAG export那样qps.nl/qimera

9. Frequently Asked Questions

What is the standard contour interval for IHO Order 1a charts?

For depths <10 m, 0.5 m intervals; for 10‑30 m, 1 m intervals; for >30 m, 2‑5 m intervals depending on scale.

How do I add hillshade to my bathymetric surface?

In QGIS: Raster → Terrain Analysis → Hillshade. In Qimera: Surface → Illumination. Combine using transparency (e.g., 50% hillshade over colour ramp).

Can I create a navigational chart (S‑57) from my data?

Yes, with CARIS S‑57 Composer or SevenCs ENC Designer. However, this requires additional cartographic knowledge and validation.

Why does my contour map look jagged?

Either your grid cell size is too small relative to noise, or you need to apply a smoothing filter. Try a median 3x3 filter before contouring.

What is the difference between a BAG and a GeoTIFF?

BAG (Bathymetry Attributed Grid) stores depth, uncertainty, and tracking list per cell. GeoTIFF stores only a single value (e.g., depth). BAG is preferred for archival and re‑processing.

10. Action Items & Next Steps

📌 Generate contours from your cleaned surface using the recommended interval.
📌 Create a colour‑shaded map with hillshade and export a GeoTIFF.
📌 Use the contour interval calculator with your survey depth range.
📌 Proceed to Day 32: Volume Calculation for Dredging.

🗺️ Day 31: Final Chart Creation and Exporting Deliverables