SHOM Raster GeoTIFF Marine Chart – World Map

Introduction

Are you looking for a SHOM digital raster GeoTIFF marine chart covering the entire world or a very large maritime area? A marine world map provides a small-scale cartographic representation offering a global view of the oceans, continents and major maritime areas. In raster GeoTIFF format, this charting can be integrated into compatible navigation or charting software to provide a georeferenced representation of the chart.

A nautical world map is particularly useful for planning long-distance navigation, ocean crossings, round-the-world voyages or for obtaining an overall view of a maritime route. It allows sailors to visualise large distances, oceans, continents and major navigation areas before moving on to more detailed charts for the different stages of a voyage.

A SHOM raster GeoTIFF world map therefore forms part of a global approach to digital charting, complementing larger-scale charts used for coastal navigation and port approaches.

What is a SHOM raster GeoTIFF marine chart?

A raster GeoTIFF marine chart is a digital representation of a nautical chart in the form of a georeferenced image.

The term “raster” refers to an image made up of pixels. Unlike vector charting, where geographical objects are stored as individual data elements, raster charting preserves the graphical representation of the chart.

The GeoTIFF format adds georeferencing information to the image. Compatible software can therefore determine the geographical position corresponding to each part of the image.

A SHOM raster GeoTIFF chart can thus be used in a compatible digital environment to view a representation of nautical charting and prepare navigation.

It is important, however, to distinguish a true GeoTIFF from a standard TIFF file. A conventional TIFF is primarily an image format, whereas a GeoTIFF also contains information allowing the image to be geographically positioned.

What is a digital marine world map used for?

A marine world map is primarily an overview chart. Its purpose is to represent a very large geographical area on a single document, with a level of detail appropriate for a global view.

It can be used to:

• plan a round-the-world voyage;

• visualise an ocean route covering thousands of nautical miles;

• compare different routes between continents;

• identify the world's major oceans and maritime regions;

• prepare an ocean crossing;

• organise a long-term sailing programme;

• obtain an overall view of a network of maritime routes;

• work on the geographical representation of a maritime project.

A world map is not intended to replace the detailed charts required for coastal navigation or port approaches.

The SHOM world map for planning a circumnavigation

Planning a round-the-world sailing voyage is a typical example of the use of a marine world map.

A sailor can first represent the entire route on a global chart: Europe, the Atlantic, the Caribbean, the Panama Canal, the Pacific, Asia, the Indian Ocean, the Red Sea, the Mediterranean or other routes depending on the itinerary.

At this scale, the world map provides an understanding of the overall organisation of the voyage and the major distances between its different stages.

It can also be used to compare several route options before selecting the detailed charts required for each section.

For example, a sailing project from France to French Polynesia can first be viewed at global or ocean scale before progressively examining the Atlantic, Panama Canal and Pacific navigation areas in greater detail.

Marine world chart and ocean crossing planning

An ocean crossing requires chart preparation adapted to the distance involved.

A world map provides an overall view of the crossing and helps identify the main geographical points along the route.

It can be used to prepare:

• an Atlantic crossing;

• a Pacific crossing;

• an Indian Ocean crossing;

• a route between Europe and Australia;

• navigation between the Americas and Asia;

• a round-the-world sailing project.

At this scale, the chart is primarily used for planning and general route representation. When the vessel approaches a coastline, archipelago or port, larger-scale charts become necessary.

Why use the raster GeoTIFF format?

The raster format has the advantage of preserving the graphical appearance of the chart.

For users accustomed to paper charts, raster representation can be particularly intuitive: symbols, colours, contours, soundings and other cartographic elements appear in a form similar to that of the original chart.

The georeferencing information also allows the chart to be used in a compatible digital environment.

GeoTIFF can therefore be relevant for navigation and charting software capable of importing and using this type of data.

Compatibility nevertheless depends on the software, its version and the precise characteristics of the file.

Using a world map with navigation software

SHOM raster GeoTIFF marine charts can be used with certain compatible navigation and charting software, including Adrena or ScanNav, depending on the versions and configurations involved.

Before using a GeoTIFF world map, it is advisable to check:

• the exact file format;

• the georeferencing information;

• software compatibility;

• the chart reference;

• the projection used;

• the resolution;

• the licence and terms of use.

Software capable of opening TIFF images is not necessarily capable of correctly exploiting all the geographical information contained in a GeoTIFF. Cartographic compatibility should therefore be verified precisely.

Raster world map and vector charting

A raster world map also differs from a global vector chart.

In a raster document, the cartographic information is represented as an image. The navigator therefore sees the graphical representation of the chart.

In vector charting, geographical elements are stored as individual digital objects. The software can then manage different cartographic objects separately according to its capabilities.

The choice between raster and vector depends in particular on the software used, the navigation equipment and the intended purpose.

For a general view of the world's maritime areas and a cartographic representation similar to a traditional chart, raster GeoTIFF is an appropriate solution when supported by the software.

A world map does not replace detailed marine charts

It is essential to understand the limitations of a world map or nautical planisphere.

The very small scale required to represent the entire world does not allow the same level of detail as a coastal or port chart.

A world map can therefore be used to:

• visualise an overall route;

• plan an ocean crossing;

• understand major geographical areas;

• plan a long-term itinerary.

However, it should not be considered sufficient for:

• entering a port;

• navigating through a narrow channel;

• transiting a reef pass;

• navigating between closely spaced islands;

• carrying out a detailed coastal approach.

For these situations, larger-scale charts are required.

Marine world map and round-the-world voyage planning

For a circumnavigation project, the world map can represent the first level of a more comprehensive charting strategy.

The navigator can first determine the major stages:

1. departure area;

2. first ocean crossing;

3. main stopovers;

4. strategic passages;

5. transition from one ocean to another;

6. tropical or temperate navigation areas;

7. return to the starting point.

Each sector can then be studied using more detailed charts.

This approach maintains consistency between the global view of the voyage and the detailed preparation of each stage.

Essential complementary information

A digital marine chart, even when georeferenced, does not by itself provide all the information required for navigation.

Depending on the voyage, the navigator must also consider:

• weather forecasts;

• wind and swell;

• currents;

• tides;

• Notices to Mariners;

• local regulations;

• recently reported hazards;

• nautical publications appropriate to the planned navigation.

The world map is therefore primarily a general charting resource. It should be integrated into a more comprehensive navigation preparation process.

How to choose a SHOM raster GeoTIFF marine world map?

Before using a digital world map, several factors should be checked.

Geographical coverage: check the exact extent of the document and the areas actually represented.

Scale: a world map is intended for an overall view and does not provide the level of detail of a coastal chart.

SHOM reference: identify precisely the chart document being used.

Format: verify that the file is a georeferenced GeoTIFF rather than a standard TIFF image.

Software compatibility: check that the navigation software can use the file and its geographical information.

Projection: consider the cartographic projection used, particularly when working with a global representation.

Terms of use: comply with the licence and usage conditions associated with the digital file.

Conclusion

A SHOM raster GeoTIFF marine world map is a digital charting resource designed to provide a global view of maritime areas and major ocean routes.

It can be particularly useful for planning an Atlantic, Pacific or Indian Ocean crossing, organising a round-the-world sailing voyage, comparing different routes or simply obtaining a general geographical representation of the world's maritime domain.

Its raster format preserves the graphical representation of the chart, while georeferencing allows it to be positioned within compatible software.

The world map should nevertheless be considered an overview tool. For coastal navigation, port approaches, archipelago passages or areas with closely spaced hazards, larger-scale charts are essential.

Effective use of a GeoTIFF marine world map therefore relies on combining a global overview with detailed charting, up-to-date nautical information and weather data appropriate to the intended voyage.

FAQ – SHOM Raster GeoTIFF Marine World Map

What is a SHOM raster GeoTIFF marine world map?

It is a digital and georeferenced representation of a very small-scale marine chart providing a global view of the oceans, continents and major maritime areas.

What is a digital marine world map used for?

It is primarily used to obtain an overall view of maritime areas, plan ocean crossings, visualise a round-the-world route and organise the major stages of a sailing project.

Can a SHOM GeoTIFF world map be used for a round-the-world voyage?

It can be used for general circumnavigation planning and for visualising the overall route. However, it does not replace the larger-scale charts required for coastal approaches, ports, archipelagos and detailed navigation areas.

What is the difference between a world map and a detailed marine chart?

A world map covers an extremely large geographical area and uses a small scale. A detailed chart covers a much smaller area and can represent more information required for coastal or port navigation.

Can a SHOM GeoTIFF world map be used with Adrena?

It may be usable with a compatible version of Adrena, depending on the exact characteristics of the file and software. Exact compatibility should be verified before use.

Can a SHOM GeoTIFF world map be used with ScanNav?

Compatible ScanNav configurations may allow the use of georeferenced raster data. The compatibility of the GeoTIFF file and the software version being used should nevertheless be checked.

What is the difference between a TIFF file and a GeoTIFF?

A TIFF file is primarily an image file. A GeoTIFF also contains georeferencing information that allows compatible software to position the image according to its geographical coordinates.

Does a GeoTIFF world map provide weather information?

No. A marine chart provides cartographic and hydrographic information. Weather forecasts, wind, swell, cyclones and other real-time information must be obtained from appropriate meteorological sources.

Is a SHOM world map sufficient for an ocean crossing?

It can be useful for general planning and route visualisation, but an ocean crossing will generally require charts covering the different areas and scales encountered, particularly for approaches and stopovers.

Why use a digital marine world map to plan a round-the-world voyage?

It allows the entire route to be visualised on a single representation, helps identify the major oceans and strategic passages, makes it possible to compare broad route options and provides a basis for detailed chart preparation for each stage.