MEMO

Specifications Measurement Dataset

Background

The Covadem project (cooperative navigable depth measurements – Coöperatievevaardieptemetingen) was launched in April 2013. The project is aimed at sharing real-time navigable depth measurements, that skippers can use to navigate more efficiently in the future and make maximum use of the navigable area provided by the waterway.

This is done as follows: Inland waterway vessels are provided with a basic on-board computer to read the data from existing sensors. Sensors such as the echo-sounder, loading gauge, GPS and fuel gauges. This datais combined into a message and send to shore. Based on these measurements, the real-time measured keel clearance is converted into the real-time water depth of the route being navigated. These real-time navigable depth measurements are made available to skippers so that, in future, this data can be used for predicting the waterdepths of the route to be navigated. Skippers can use real-time, accurate waterdepth to navigate a more efficient route. More efficiently, because sailing on deeper water consumes less fuel.

Measurement Dataset

The dataset consists of the following files:

  • grid-only-rotterdam-waal.kml: ASCII based file for the area containing the depth measurements askml formatted file format.
  • measurementset.csv: ASCII based filewith all the depth measurement data of sailing ships.
  • databaseSet.xml: ASCII based file in xml format describing the area and the containing measurements for each area.

The measurement dataset (measurementset.csv) consists of real-timedepth measurements; data from existing sensors, such as the echo-sounder, loading gauge, GPS and the fuel usage. The measurement data set contains valid data of sailing ships only. Sailing ships are those ships with an average GPS speed over ground of over 1 km/hour for at least 10 minutes.

The measurement dataset measurement data is collected between August 1st00:00:00 and August 31st23:59:59. Measurements are recorded with a time period of 1 minute.

Each measurement is uniquely identified with a measurement id.

Each measurement has a time stamp at which the measurement was taken.

Each measurement has a GPS location where the measurement was taken.

Each measurement has a ship ididentifying the ship, being the source for the measurement.

The Measurement Dataset is an ASCII based file. Each depth measurement is on a single line. The depth measurement parameters are comma separated. The first line in the file holds the header line to identify the each depth measurement parameter.

Measurement Dataset Parameters
Parameter / Description / Type
id / Unique identification for this measurement / Long
example: 870428521
shipid / Identification number for the ship / Integer
Example: 35
date / The date and time of this measurement / Date; format
yyyy-MM-dd-HH:mm:ss
example: 2015-07-31-23:55:23
lat / GPS latitude position in decimal degrees, coordinate system is WGS84 / float; format FF.ffffff
example: 51.833398
lon / GPS longitude position in decimal degrees, coordinate system in WGS84 / float; format FF.ffffff
example: 6.184142
sog / Speed Over Ground, the speed measured by the GPS in km/hour. / float; format FF.ff
example: 10.59 km/hour
heading / Heading measured by the GPS in degrees, range between 0 – 360 degrees. North = 0; / float; format FFF.ff
example 189.45 degrees
hdop / Horizontal dilution of precision for this GPS measurement.The idea of Geometric DOP is to state how errors in the measurement will affect the final state estimation. See meaning of dop values for details. / float; format FF.f
example: 2.0
vdop / Vertical dilution of precision for this GPS measurement.The idea of Geometric DOP is to state how errors in the measurement will affect the final state estimation. See meaning of dop values for details. / float; format FF.f
example: 1.6
stw / Speed Through Water, the speed of the ship relative to the water, in km/hour. / float; format FF.ff
example: 9.75 km/hour
ukc / The underkeel clearance in meters. The underkeel clearance is the vertical distance between the bottom of the hull and the bottom of the river. / float; format FF.ff
example: 12.56 meter
waterdepth / Waterdepth is the calculated waterdepth for this position. It uses the ukc, the ship’s draft and the speed through water to calculate the waterdepth, in meters / Float; format FF.ff
example: 5.67 meter
cargo / The weight of the cargo loaded on this ship, measured in tons. / float; format FFFFF.f
example: 2543.5 tons
draftaft / Thedraft at the aft of the ship. The draftof the ship'shullis the vertical distance between thewaterlineand the bottom of the hull (keel), in meters / float; format FF.ff
example: 1.56 meter
draftforward / Thedraft at the bow of the ship. The draft of the ship'shullis the vertical distance between thewaterlineand the bottom of the hull (keel) in meters / float; format FF.ff
example: 1.68 meter
fuelflow / The amount of fuel flow measured in liter/hour / Float; format FFF.ff
example: 123.56 liters/hour

Additional information

Meaning of DOP values

DOP Value / Rating / Description
< 1 / Ideal / Highest possible confidence level to be used for applications demanding the highest possible precision at all times.
1-2 / Excellent / At this confidence level, positional measurements are considered accurate enough to meet all but the most sensitive applications.
2-5 / Good / Represents a level that marks the minimum appropriate for making business decisions. Positional measurements could be used to make reliable in-route navigation suggestions to the user.
5-10 / Moderate / Positional measurements could be used for calculations, but the fix quality could still be improved. A more open view of the sky is recommended.
10-20 / Fair / Represents a low confidence level. Positional measurements should be discarded or used only to indicate a very rough estimate of the current location.
>20 / Poor / At this level, measurements are inaccurate by as much as 300 meters with a 6 meter accurate device (50 DOP × 6 meters) and should be discarded.

The measurement dataset contains measurements from ships within the boundaries of the measurement area.

Figure1Measurement Dataset Area

Figure 2 Example of the Measurement Dataset

Figure 3 Example of the Measuerment Dataset ASCII file

Figure 4 Example of the xml formatted Measurement Dataset

Page 1 of 4