Hi all, I started a new thread so these links can be easily found in the
future. This builds on a recent thread on permissible data sources to answer 3
questions: (1) Which data layers from the Vic gov contain State Forest (SF)
boundary data? (2) Which of these layers do we have permission (with waiver) to
use? (3) Do these permissions enable editors to use of State Forests boundaries
on the Vic gov MapShare site? Happy to hear back from everyone and to fix up
any stuff-ups.
As stated on the Aus data catalogue and confirmed on the forum by Andrew
Harvey, we have a waiver to use all of the CC by 4.0 datasets that are listed
on DELWP's Vic Map catalogue. (I'll call these the 'core' VicMap datasets for
brevity). DELWP has many other CC4.0 datasets that we don't have explicit
permission to use according to the Aus data catalogue (I'll call these
'non-core' DELWP/VicMap data).
Aus data catalog: https://wiki.openstreetmap.org/wiki/Australian_data_catalogue
DEWLP VicMap Catalogue:
https://www.land.vic.gov.au/maps-and-spatial/spatial-data/vicmap-catalogue
Core VicMap datasets
I checked through the metadata files and/or downloaded the GIS datasets for all
of the core VicMap datasets to try to find a full set of State Forests
boundaries. The core VicMap files contain 3 versions of the State Forests
boundaries.
The VicMap Lite dataset [VMLite_PUBLIC_LAND_SU5] has a simple, low-res dataset
that shows the boundaries of all SFs and other types of public land. It doesn't
show their names. A single polygon might contain many contiguous SFs (each of
which has a different name in reality). The dataset is old, and was last
updated in 2008. The Lite datasets were intended for use at broad zoom levels
on web devices. The dataset isn't much use for our purposes (although some of
the Lite boundaries are of comparable 'accuracy' to some of the coarser SF
boundaries that currently exist in osm.)
https://www.land.vic.gov.au/maps-and-spatial/spatial-data/vicmap-catalogue/vicmap-lite
The VicMap Crown Land Tenure dataset [CL_TENURE_VIEW] is where you'd expect to
find SF boundaries. It does contain some, but it's a mess. Most SFs aren't
included in the dataset, and when the dataset is compared against more recent
(non-core) DELWP data, there doesn't seem to be any rhyme or reason to why most
SFs were omitted. [I'm guessing that this resulted from inter-agency rivalries
between DELWP and the privatised VicForests, but that's speculation on my part.
Public land tenures other than SFs seem to be well represented on the Crown
Land Tenure map and are also shown on a few other core datasets. SFs are
conspicuously absent.]
https://www.land.vic.gov.au/maps-and-spatial/spatial-data/vicmap-catalogue/vicmap-crown-land-tenure
The VicMap Property dataset (VMPROP.PARCEL_CROWN_APPROVED) contains detailed,
accurate boundaries of all land parcels on crown lands. But it doesn't show
which parcels are in SFs and which are other crown lands. Nevertheless, if
local editors know where a SF is on the ground, this dataset does provide
accurate boundary data which could be used I guess. This dataset can also be
accessed and data subsets can be downloaded in MapShare.
https://www.land.vic.gov.au/maps-and-spatial/spatial-data/vicmap-catalogue/vicmap-property
More recent, non-core DELWP datasets
The best sources of boundaries for SFS and other public lands are two, recent
datasets: (1) Public Land Management (PLM25) and (2) Public Land Management
(PLM25) Generalised.
https://discover.data.vic.gov.au/dataset/public-land-management-plm25
https://discover.data.vic.gov.au/dataset/public-land-management-plm25-generalised
PLM25 is described as "... a derived layer, using VMPROP.PARCEL_CROWN_APPROVED
as the base layer. It relies on tabular and spatial sources to get the land
description. PORTAL, PRIMS are the tabular sources of information. PARKRES,
VEACRECS25 and CL_TENURE are the spatial sources. <i>Additional layers were
also created to describe areas of state forests</i>, plantations, water
frontages and commonwealth land." [my italics]
The "generalised" dataset is said to have fewer tags and some dissolved
boundaries. However, the line work for the two seems to be identical, and
equally precise along complex, curved boundaries, with one key difference. Many
SFs contain a number of parcels of land, some contiguous (i.e. adjoining with
shared boundaries), and some adjacent, but separated by easements. In both
datasets, adjacent parcels that are separated by easements are shown as
separate polygons. However, the base PLM25 dataset also contains separate
polygons for contiguous, adjoining parcels that have shared boundaries, whereas
the Generalised dataset dissolves all the internal boundaries to form one
single polygon for the contiguous parcels.
(Hope this makes sense. If not, imagine two rows of 5 residential house blocks
on opposite sides of a road, giving 10 houses in total. Now imagine that these
house blocks (=land parcels) are in a SF and the ‘road' is a gov easement. In
the PLM25 dataset, every house block (land parcel) would be shown as a separate
polygon, giving 10 polygons in total, each tagged as part of the SF. In the
Generalized dataset, all of the house blocks on one side of the street would be
combined into one polygon, and those on the other side would be in another
polygon, giving 2 polygons in total, both tagged as being part of the SF.).
Apart from this , and fewer fields/tags, the two datasets seem identical.
The two PLM datasets can be downloaded as GIS datafiles or viewed as WMS files,
which could be used as a base layer image in iD or JOSM to trace boundaries
from, for those who don't use a GIS. The dept provides wms files for the SFs
boundaries (i.e. excluding other types of public land) at:
https://discover.data.vic.gov.au/dataset/state-forest-public-land-management-wms
https://discover.data.vic.gov.au/dataset/state-forest-generalised-public-land-management-wms
PLM25 vs VicMap Crown Land Tenure
As noted earlier, the VM Crown Land Tenure dataset contains only a fraction of
the SFs in Vic. This image - https://imgur.com/E6FtbB1 - compares the two
datasets. The Blue areas show all SFs in Vic, as provided in the new PLM25
dataset. The Red polygons show all polygons in the older Crown Land dataset
that overlie SF boundaries that are shown in PLM25. (Thus all red patches have
a blue patch beneath them). As can be seen, most SFs in the new PLM25 dataset
are not shown in the older, core VicMap Crown Land Tenure dataset that we have
permission to use.
MapShare boundaries
MapShare contains a copy of the SF boundaries. On MapShare, users can click on
a polygon (or point or line), add it to a 'drawing layer', add more polygons to
the drawing layer, and then download a shape file that contains all of the
features on the drawing layer. Hence, a user could download the complete
boundary files for one or more SFs. This raises the question, which DELWP
dataset is used in MapShare? As best I can tell, MapShare uses the detailed
PLM25 dataset. When you click inside a SF, each parcel of land inside a SF
forms a separate polygon, as in the PLM25 dataset and not the Generalised
dataset. The source data is derived from a "State Forest Holding Layer", which
is the same field name used in the PLM datasets, but not in the older VicMap
Crown Land Tenure dataset. The boundaries are extremely precise and definitely
aren't derived from the older, generalised 'Lite" dataset.
Implications for OSM
The PLM25 and PLM25 Generalised datasets contain the most accurate SF
boundaries. I'll leave it to the group to decide whether these are covered by
the existing waiver. If not, it would be great to get permission to use them.
These would be the best datasets to use if a formal import of SF boundaries was
ever considered. If the PLM25 dataset is considered to be not covered by the
existing waiver, then I imagine it would also be considered to be inappropriate
to get SF boundaries from MapShare.
We do have a waiver for the VicMap Crown Land Tenure dataset but I suggest that
editors avoid using this data for SF boundaries. Most SFs aren't on it anyway,
as the image above shows.
We also have a waiver for the Vic Property and VicMap Lite datasets (although
VicMap Lite isn't listed on the Aus data catalogue atm). If editors are keen to
improve the accuracy of boundaries of a local forest, the boundaries in the
VicMap Lite dataset, while coarse when compared to the PLM25 data, may still be
much better than some of the coarsest approximations to SF boundaries that
currently exist in osm. If matched to features on satellite images, the VicMap
Lite data could still provide a useful way to refine existing boundaries.
Similarly, if you're really keen, boundaries could be extracted from the Vic
Property dataset (which is on MapShare), although it would take some work to
match these to on-ground boundaries.
Hope this helps. Thanks to everyone who provided suggestions on the earlier
topic thread. I'm happy to chase up more info if it's useful. Cheers Ian
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