INTRODUCTION: ROV operations, TV-sled tows or lander deployments are nowadays common procedures for studying hydrothermal vents, cold seeps or other environments/habitats that demand very detailed visual observations and sampling techniques. Having online the position of the ship and the underwater device (e.g. ROV, lander) together with a bathymetric map of the area on a screen makes it much easier to deploy the device at the best possible sampling position. Over the last 11 years the software package OFOP has been developed to do exactly this, bearing user-friendliness in mind. OFOP has mainly been developed with the experience of scientific cruises as its basis and aims to fit the needs of a wide variety of marine science experts: helping geophysicists when planning multibeam surveys or reconfirming positions of OBS/H's, supporting microbiologists to deploy e.g. TV-guided multi-corers on a bacterial mat; helping biologists visually mapping habitats or oceanographers towing CTDs through hydrothermal plumes to know exactly where the CTD is at any given time.

OFOP reads a wide variety of position data and formats (NMEA-0183, NMEA-equivalent serial strings like SAG from Posidonia or GAPS underwater navigation systems, HRP and camera view direction from ROV's, …). Setting way points, creating routes and plotting of digitally recorded seafloor observations helps to define targets for the next deployments and makes later GIS-based data analysis possible. Writing Ocean Floor Observation Protocols in OFOP simply demands clicking buttons that record all input parameters (GPS-position, underwater position of the deployed gear, and other connected data streams) and station actions, when e.g. the device has reached the seafloor or crosses a seep site with tubeworms. All actions are stored locally in simple-to-read text files and can be broadcast to the local network via UDP at the same time. Detailed post processing is possible by replaying the recorded seafloor video which is linked to the recorded navigation and position data.

The post processed observation files can be merged with previous ones and additional sensor data can be integrated, corrected for time offsets and finally splined to get a complete data set for each individual deployment. Seafloor observation items are retrieved from an editable item list that gives each item an individual ID number. Each of the 28 buttons can be linked to a specific observation item (e.g. bacterial mat, bubbles, seep, soft sediment, etc.) and 6 different lists of up to 100 entries can be used to categorize the more specific observations (e.g. Ascidina (solitary), Orange Roughy, Pebbles, …). All data from previous observation tracks can be plotted online with the current deployment and thus help tremendously to find and re-find a particular spot at the seafloor. Special requirements can be accomodated by adding features in new windows and input/output capabilities can be adapted to individual needs.

Control over the positioning of devices that are deployed (coring or lander systems), towed over (TV-sleds, toyo CTDs) or work at the seafloor (ROVs) is essential for the success of the deployment. Easy online logging of sea floor observations helps to decide where additional deployments should be undertaken and is the basis for later GIS-based spatial analyses.

Background maps are loaded as images (jpg, bmp, wmf). Once calibrated, they can be reloaded easily. Various tools for distance measurement, multi beam planning, offset calculation for e.g. moored equipment help during the navigation. Several data sets of waypoints and routes can be loaded, manipulated and exported. The post-processing options in OFOP allow to:

• edit, smooth and spline navigation data (e.g. needed for underwater positions)
• replay the seafloor video and display the linked position data information on the map at the same time
• perform detailed digitising (logging) of seafloor observations with the replay option
• merge other data with the processed navigation data (e.g. memory CTD data) and seafloor observations carried out by different specialists

All logged data are saved as "easy-to-read and import" ASCII-text files to allow maximum compati-bility with other software (e.g. EXCEL, ACCESS, SURFER, ARC GIS, data bases in general). OFOP allows input and output via serial and / or network connections (UDP). Three different positions can be displayed and logged simultaneously (normally the ship and two underwater positions, e.g ROV and ROV-cage). More positions (e.g. air gun-arrays at the sea surface) can be implemented. Input support:

• NMEA style inputs (e.g. VTG, GGA, HDT, WPL, …)
• Underwater navigation input (e.g. iXSea SAG string; HPR calculation of the absolute position is carried out in OFOP)
• Heave, roll, pitch, depth, camera viewdirection output from ROV systems (e.g. sub-Atlantic overlay output)
• Special input formats as direct export from data bases (e.g. Werum DVS, RV Tangaroa DAS)
• Other input formats can be easily implemented

Output support:

• Export of all incoming strings via serial and/or network connection
• OFOP data string for broadcasting to other OFOP-computers in the local network
• Fledermaus-compatible string to visualize the ship, ROV and cage position in 3D Writing and logging individual protocols for each deployment is made easy.

After creating a new protocol the operator only has to press one button to log the start time of the deployment, the time the gear reaches and comes off the bottom and when it finally is safe back on deck. For each of these events all available data are stored in a separate protocol text file (*_prot.txt). In addition, the operator can log features of the seafloor (e.g. soft sediment, rock, clams, ...), which are represented as buttons and 6 list fields, each of which can hold up to 100 entries. The label for each of the buttons as well as the content of each list can be manipulated by the operator before or during the deployment. Each entry in the so-called "Button File" gets a unique ID number that is later used for processing purposes (with OFOP or other software packages).

Waypoints and routepoints can be created by clicking on the map. The various tools help to show distances to other waypoints graphically, line spacing of multibeam tracks, the length of the route or the last part of it, as well as helplines with user-defined orientation and distances. Windows for special purposes make operations easier and ensure a complete and detailed recording of positions, time, event. One of these windows is the CTD-Deployment window. It can be used to plan in which water depth bottles should be closed and will write all position and depth data into the protocol when the button "Bottle Fired" is pressed. At the same time it creates a waypoint file that saves these positions for later use.

Another special purposes window is the Cherokee Orientation window. It establishes the serial connection to the video overlay data that contain information about the heading, depth, heave, roll and pitch of the ROV but also the view-direction of the camera. All information is stored and the view direction of the camera is displayed online as a line pointing away from the ROV position on the OFOP map. Previous observation can be plotted as color-coded dots during deployments at any time. An unlimited amount of observation files can be loaded and the observations (up to 10 at a time) can be chosen via their ID numbers. Positions, when e.g. the device reached the bottom or where photos were taken can be shown as labelled dots (the respective photo number is displayed).The flexible and easy use makes this feature an ideal tool for detailed mapping of different geological structure, habitats, trawling-impact, etc.. The spatial resolution is linked to the 1-second splining interval of the position update that is introduced during the postprocessing. Nevertheless several observations can be stored and displayed for the same position / time-spot.

Postprocessing possibilities include merging of additional data sets as e.g. memory devices like CTDs or other logging sensors. This is done by loading column-based ASCII files containing as many columns as there are data sets. Various files can be loaded after each other. Each file has to have date and time information which is used to add it at the correct time slot. The time resolution is one second.

All data sets can be edited graphically by deleting outliers, e.g. from underwater navigation errors, and they can be smoothed via a moving average with a selectable window width. As a final step data gaps can be filled via a linear spline algorithm (other algorithms can also be implemented).

Time offsets between the data recorded online and those from logging sensors can easily be corrected by shifting the respective data set back and forth in time. The result is immediately displayed graphically and can be used for checking if the offset correction is correct (e.g. comparing the depth values of a memory CTD with the depth values of the underwater navigation system).

OFOP also allows to replay videos (e.g. avi, mpg) in various speeds or frame by frame. Loading the corresponding track information links the video directly to the position information. In replay mode, all available information is fed into OFOP as during the live deployment. The seafloor can be studied and observations can be digitized again in the same way as during the live deployment. This allows experts from different disciplines to combine their observations and get a full inventory of what can be seen at the seafloor.

The software was mainly written to make navigation and data logging easier during scientific cruises. Implementing features that are of direct use during cruises resulted in a collection of functions and tools that make the planing of deployments, the navigation and protocol writing simple and intuitive.Nowadays OFOP is often used for seafloor habitat mapping. For this the replay option and button-based logging possibilities of OFOP are used as well as the editing, smoothing and splining of track data.

OFOP itself does not come with any video codecs, it only uses what is installed on your machine. Thus if OFOP does not play your video or not correctly (not giving a time) you have to install the correct codec. The list below gives some links to webpages that hopefully help to fix your problems.

OFOP 3.3.3g