Early topo map work for Taiwan

[islandee]

I'm looking into the very sketchy history of a Japanese who was later identified as a "spy" operating in Southeast Asia. His main contributions during his career seem to have been in the mundane field of land (terrain) and route surveying. His first assignment was in Taiwan in 1896 where he worked for the Land Survey Department of General Staff Headquarters. He went there with no experience. I don't know if he went as a civilian or as a member of the IJA. I'm curious as to what his contribution might have been.

Context: Japan acquired Taiwan in 1895 per the Shimonoseki Treaty which settled the First Sino-Japanese War. Three years later, in 1898, Japan issued a set of 1:200,000 scale topographical maps of the island. They were dated 1897, so in actual fact, Japanese field work and engraving would have been completed in about two years. That seems like a rather tight schedule: admittedly it would have been partly a function of manpower, but I doubt that the Japanese Army had enough personnel trained in terrain surveying to meet that schedule. I'm wondering if the Japanese Army for this first effort had simply built on existing Chinese topo maps, doing random spot field checks to verify accuracy, rather than starting from scratch, with no data. This approach was regularly used by Japan later in Southeast Asia in the buildup to WWII. Had China issued topo maps for Taiwan of scale approximately 1:200,000 or better before 1895?

For a comparison, note that Japan did not start issuing 1:50,000 scale topos of Taiwan until thirty years later, in 1925. Recall also that aerial photography / photogrammetry, such as it existed at that time, relied on hot-air balloons --- not practical for large land mass survey work.

I thank you for any information you can provide regarding this topic.