💾 DAY 84: DATA EXPORT FORMATS – CAD, GIS, 3D

⏱️ Estimated Reading Time: 15 Minutes | 🎓 Level: Professional Hydrographer / Data Manager

From Grid to Deliverable – Choosing the Right Format for Every Client

Instructor: Engr. Rokib Hossain | River Warrior Academy

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🏠 Course Homepage

📖 Table of Contents (Serialised)

• Why Export Format Matters More Than You Think
• Format Comparison: GeoTIFF, BAG, XYZ, DXF, Shapefile, S‑57, LAS, 3D PDF
• Interactive Export Format Recommender & Size Estimator
• Raster Formats (GeoTIFF, BAG, GRD)
• Vector Formats (Shapefile, DXF, GeoJSON)
• 3D Formats (LAS, 3D PDF, OBJ, U3D)
• Specialized: S‑57 (ENC), XTF, GSF
• Case Study: Bay of Bengal Multi‑Format Delivery
• Data Export Checklist
• Resources & Software
• Frequently Asked Questions (with internal links)
• Action Items & Next Steps

1. Why Export Format Matters More Than You Think

Delivering data in the wrong format is as bad as delivering inaccurate data. Engineers need DXF for AutoCAD, GIS analysts need Shapefiles, and hydrographic offices require BAG or S‑57. Knowing the strengths and limitations of each format ensures client satisfaction and avoids rework. This day covers the most common export formats used in hydrography, and provides a decision framework.

🧠 Golden Rule: Always ask the client for their preferred data format before processing. Never assume – a last‑minute conversion may lose metadata or require re‑exporting.

🌊 River Warrior Pro-Tip: Format Standardisation

For Bay of Bengal projects, we deliver a standard package: GeoTIFF (raster), Shapefile (contours), BAG (archival), and a 3D PDF for non‑technical stakeholders. This covers 95% of client needs.

2. Format Comparison: GeoTIFF, BAG, XYZ, DXF, Shapefile, S‑57, LAS, 3D PDF

.htmlBAG那样Raster (bathymetry)那样Archival, uncertainty preservation那样Full (TPU, tracking list, metadata)那样Hydrographic archives, IHO.htmlXYZ (ASCII)那样Point cloud那样Simple point data, volume calculations那样None那样Custom analysis, legacy systems.htmlShapefile (.shp)那样Vector那样Contours, depth points, boundaries那样Limited (prj, dbf)那样GIS, ESRI products.htmlDXF (AutoCAD)那样Vector (CAD)那样Contours, breaklines, cross‑sections那样Minimal那样Engineering design (dredging, ports).htmlS‑57 (ENC)那样Vector (nautical)那样Electronic Navigational Charts那样Extensive (IHO S‑57)那样Official charting.htmlLAS/LAZ那样Point cloud (LiDAR)那样LiDAR and MBES point clouds那样Full (classification, intensity)那样Detailed modelling, feature extraction.html3D PDF那样3D model那样Visualisation, client presentations那样Embedded model metadata那样Non‑technical stakeholders

Format	Type	Best for	Metadata support	Typical use case
GeoTIFF那样Raster那样Gridded bathymetry, colour maps那样Embedded georeferencing那样GIS, backdrops

📦 Export Format Recommender & File Size Estimator

Select your data type and client requirement, get format recommendation and approximate file size:

Data type: Bathymetric grid (1 m cell, 10 km²) Point cloud (1 point/m², 10 km²) Contour lines (1 m interval, 10 km²)

Client need: GIS analysis CAD design (dredging/construction) Official archive (IHO) 3D visualisation (non‑technical)

Recommended format: GeoTIFF (grid). Estimated file size: ~40 MB.

3. Raster Formats (GeoTIFF, BAG, GRD)

• GeoTIFF: Most versatile for GIS. Supports 32‑bit floating point, georeferencing, and compression (LZW). Ideal for colour‑shaded bathymetry.
• BAG (Bathymetry Attributed Grid): IHO standard. Stores depth, uncertainty, and tracking list per cell. Required for many hydrographic archives.
• GRD (Golden Software): Used by Surfer and some older software. ASCII or binary.

💡 For GeoTIFF, include a .tfw world file if the internal tags are missing. Most modern software embeds them.

4. Vector Formats (Shapefile, DXF, GeoJSON)

• Shapefile (.shp): De facto standard for GIS. Delivered as a set of files (.shp, .shx, .dbf, .prj). Contours, depth points, boundaries.
• DXF (AutoCAD): Used by civil engineers. Contours as polylines, depth points as text. Units must be consistent (e.g., metres).
• GeoJSON: Web‑friendly, lightweight. Good for online maps and modern GIS.

📐 For DXF, always include a metadata text block in the drawing (datum, projection, contour interval).

5. 3D Formats (LAS, 3D PDF, OBJ, U3D)

• LAS/LAZ (point cloud): Industry standard for LiDAR and MBES point clouds. Stores classification, intensity, and returns. Use LAZ for compression.
• 3D PDF (U3D/PRC): Interactive 3D model embedded in PDF. Viewable with free Adobe Reader. Great for presentations.
• OBJ / STL: Used for 3D printing and further modelling. Requires conversion from point cloud.

🔧 In Qimera, export point cloud as LAS. In CARIS, export to 3D PDF via the “3D Flythrough” module.

6. Specialized: S‑57 (ENC), XTF, GSF

• S‑57 (ENC – Electronic Navigational Chart): Official IHO standard for nautical charts. Requires specialised software (CARIS S‑57 Composer, SevenCs).
• XTF (eXtended Triton Format): Side scan sonar exchange format. Used for mosaicking and target identification.
• GSF (Generic Sensor Format): Multi‑sensor data (bathymetry, backscatter, sidescan). Used by Kongsberg, QPS.

📌 S‑57 is complex; many clients prefer a GeoTIFF + Shapefile instead. Only produce ENC if explicitly required.

7. Case Study: Bay of Bengal Multi‑Format Delivery (2026)

Project: 200 km² offshore wind farm site survey.

• Client requirements:
  • GeoTIFF (raster) for GIS team.
  • DXF contours for civil engineering (foundation design).
  • LAS point cloud for detailed modelling.
  • BAG for regulatory archive.
• Exports:
  • Grid → BAG (1 m, with TPU). Also exported as GeoTIFF (16‑bit).
  • Contours (1 m interval) → Shapefile and DXF (simplified for AutoCAD).
  • Point cloud (subsampled to 5 points/m²) → LAS (lossless compression).
• Result: The client praised the well‑organised delivery package; the DXF was used directly for monopile positioning.

🌊 Always include a README file explaining the coordinate system, vertical datum, and export parameters – it saves countless support emails.

8. Data Export Checklist

• Confirm client’s required formats before processing.
• Export grid as BAG for archival (if required).
• Export GeoTIFF for GIS (check georeferencing).
• Generate contour shapefile and DXF (appropriate interval).
• If point cloud needed, export as LAS with proper classification.
• Create 3D PDF for client presentation (optional).
• Write a README with metadata: projection, datum, cell size, vertical reference.
• Zip all files into a single package with logical folder structure.
• Test that at least one file from each format loads correctly in a standard viewer.
• Deliver and archive with checksum.

Click items to track progress (saved in browser).

9. Resources & Software

SoftwareExport capabilitiesLink .htmlQPS Qimera那样BAG, GeoTIFF, LAS, Shapefile, DXF, 3D PDF那样qps.nl/qimera .htmlCARIS HIPS那样S‑57, BAG, GeoTIFF, DXF, 3D flythrough那样teledynecaris.com .htmlGlobal Mapper那样Vast format conversion (raster, vector, point cloud)那样bluemarblegeo.com PDAL (open source)那样LAS to XYZ, GeoTIFF conversion那样pdal.io

10. Frequently Asked Questions (with internal links)

What is the difference between BAG and GeoTIFF for bathymetry?

BAG stores uncertainty and tracking list per cell, making it suitable for archiving. GeoTIFF stores only depth (or a single value) and is more common in GIS. Day 76 final products covers delivery.

How do I export a DXF from Qimera?

Select the contour layer, right‑click → Export → DXF. Ensure the coordinate system is set to UTM (no geographic lat/lon for CAD). Day 78 contour generation is a prerequisite.

What is the best point cloud format for large datasets?

LAS with compression (LAZ) is the industry standard. For maximum compatibility, use LAS 1.4. Day 44 LiDAR discusses point cloud processing.

Can I convert XYZ to BAG?

Yes, using Qimera or CARIS. You need to provide uncertainty estimates; otherwise the TPU layer will be empty. Day 74 TPU explains uncertainty.

Why does my DXF have no projection?

DXF does not store projection natively. Always include a separate metadata file (e.g., .prj or README). Day 31 chart creation mentions metadata.

11. Action Items & Next Steps

• 📌 Use the format recommender: select “point cloud” and “3D visualisation” – see recommendations.
• 📌 Export a small grid as GeoTIFF and as BAG; compare file sizes and metadata.
• 📌 Create a simple DXF from contour lines and open it in a CAD viewer (e.g., Autodesk Viewer).
• 📌 Proceed to Day 85: Final Survey Report & Documentation.

◀ Day 83: Tide & Datum Merging Day 85: Final Survey Report ▶

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