21
November - 2017
Tuesday
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Whiterock Cave was a major addition to the Clearwater System and together with Blackrock Cave it forms the northern development.  A good survey was critical to our understanding of the system and most importantly – where to look for new passages.  With good modern survey data available for all of the cave a number of drawing methods were possible.   In the end the team chose an innovative process, never before used by cave surveyors but one which suited the system perfectly.  This is how it was done.

Whiterock Cave was discovered in 2003 and has been the main focus of attention for the three subsequent expeditions (2005, 2007 & 2009).  It was soon connected to the underlying Blackrock cave and the Clearwater System, and rapidly became an important part of the northern Api development.  Despite this no finished cave survey had been produced by the time the team returned home after the 2009 expedition.  Several attempts were made at producing a survey using the cave survey drawing software, Therion.  Both Andrew Atkinson in 2005 and Dave Clucas in 2007-9, with the help of the team,  spent many hundreds of man hours using the programme but were unable to produce a finished product.  Despite strong arguments to the contrary it eventually became clear that traditional hand drawing methods would be a lot quicker and produce more ‘user friendly’ results.

The Mulu Caves Project took Colin Boothroyd’s brilliant hand drawn, 1989 survey of the Clearwater and Blackrock Caves and updated it with all the later discoveries at the lower end of the system.  These were mostly minor and were inked onto the original drafting film.  This gave the project a complete up to date survey of the southern end of the system.  This 2.5m long monster was then scanned in a number of industry standard formats and placed in the archive.  The style of both plan and elevation, together with the level of detail shown then became the foundation for the new Whiterock Survey.

Post expedition, work commences on the Whiterock survey. Photo © Jane Allen

The proposed new survey went through a detailed planning phase where all the decisions and methodology were determined and drawn up in a schedule before work commenced.  An early decision was made to include all of Blackrock as, at least geologically; this represented most of the lower level of the cave.  With this included, the survey could be produced with original data from the 1988 expedition onwards.  This included the work of many different surveyors over seven expeditions spanning 21 years, who contributed to the archive of field notes and drawings.  The base line data for the survey came from our Survex database, which has been built up since 2003 and has involved a large amount of work with the original notes and log books.  This dataset allowed the cave to be viewed in 3D where it became obvious that the cave had three principal levels of development.  In many places, the higher levels obscured those below, and the traditional approach of a hand drawing would leave these areas confusing and unclear.  The answer was to draw three separate survey plans representing the three principal levels, scan each one and then merge them with a software package on the computer. To ensure all passages were included a master print out was produced and colour coded into the three levels.  In fact, the outline of all three was first drawn and scanned and then the passage detail included before further scanning, six huge individual drawings in all.  A similar problem was evident with the elevation sections.  From whatever angle the cave was viewed, major passages obscured one another.  This was solved by drawing three sections, splitting the cave into Eastern, Central and Western elevations.  These were again scanned.

The pixel based (raster image) scans were tidied of artefacts in Adobe Photoshop, and then layered in the same programme. This allowed the individual layers to be tinted so that it would be clearer what level a passage or series belonged to. Points connecting the different levels were also tidied in Photoshop. The composite image was then transferred to Macromedia Freehand for lettering and addition of symbols and other information. Elevations were also added in Freehand as these had been scanned to vector files only. After final checking the Freehand file was output to print quality PDF format and emailed to the printer.

The smaller Clearwater System graphic included the use of the Boothroyd survey scan.  This together with the three ‘development levels’ graphics were produced solely in Freehand, using a low grade jpg scan of the plan to trace over passage outline. These traced ‘paths’ could all be layered and filled with appropriate colour or transparency, with further layers for text and ancillary graphics. The jpg was then discarded and the files again saved to PDF output for print.

In all, it was a huge task but one which was completed from start to finish in less than eight weeks.  The finished survey and survey graphics were displayed at the BCRA Caving Conference where they achieved an honourable mention in the cave survey award.

A low resolution version of the 2009 Whiterock survey. Survey © Mulu Caves Project