Creating Island

[DougMatthews]

Basically it is a pain that the exclusions go out to a somewhat random qmid boundary... 10,11,12,13

Not sure what you mean here. Will you please provide an example?

-Doug

 

[ahuimanu]

I think what he means is that your exclusion will touch other QMID boundaries and then you end up having a lot of water-replacement to do. In the case of my attemp to make the new Kobe airport in Japan, I have a considerable amount of retracing of coastlines to do without the benefit of FSX data for reference in GoogleEarth (or some similar product like global mapper).

 

[DougMatthews]

I think what he means is that your exclusion will touch other QMID boundaries and then you end up having a lot of water-replacement to do. In the case of my attemp to make the new Kobe airport in Japan, I have a considerable amount of retracing of coastlines to do without the benefit of FSX data for reference in GoogleEarth (or some similar product like global mapper).

Sometimes it can help to do multiple smaller exclusions rather than one big one. Also, the exclusion does NOT have to contain the targeted vector data - the exclusion's envelope (extent) just needs to intersect the targeted vector data's envelope.

-Doug

 

[ahuimanu]

In this case, would the vector data be the shoreline data? I ask because my own interests are to "cut out" an island in a bay where not island is currently depicted (again, the Kobe airport in Japan). Therefore, I assume I need to exclude the existing water, using an exclude slightly larger than my required island. Then, I need to provide the island cut-out and then follow this with replacement water.

It seems to be that the problem we are describing entails having to exclude across these QMID boundaries. Is there an alternate technique you are referring to that has not been discussed? For instance, salient to the problem of creating a new island, what vector data is involved and how is that vector data involved?

Thank you,

Jeff

 

[DougMatthews]

In this case, would the vector data be the shoreline data? I ask because my own interests are to "cut out" an island in a bay where not island is currently depicted (again, the Kobe airport in Japan). Therefore, I assume I need to exclude the existing water, using an exclude slightly larger than my required island.

In your case the vector data you are trying to exclude would be water, not shoreline.

If you look at the default vector BGL (cvx****.bgl) for the area using TmfViewer.exe you may examine the shape of the default water polygon(s) you need to remove.

The exclusion polygon does NOT necessarily need to be larger than your required island.

Create one (or more) exclusion polygon (recommend a rectangle, since the thing that matters is the bounding box of the exclusion polygon) that intersects the bounding box of the water polygon(s) you wish to exclude, and avoids (if possible) the bounding boxes of water polygons you wish to remain. Note this could be a tiny exclusion polygon that is contained (or not contained!) by the water polygon you are targeting.

Then, I need to provide the island cut-out and then follow this with replacement water.

You'll then provide replacement water polygon(s) with a hole for your island, as well as shoreline polylines if you wish.

-Doug