Solving this is going to be really tricky, since there is not one right answer. Treating channels as colour means allowing for human perception, and non-uniform scaling, hopefully within a defined colour space. Treating images as data means just numbers and math. Sometimes we want one thing, sometimes the other, and naturally we always expect the "right" answer. But there may be a trade-off, I think, between treating image channels as data, and treating them as colour. If you want to try some things out together, test data would help. as its own alpha channel (or the reverse). (I'm sure we can make transform previews work well with some thought.)Īnother technique I have sometimes used to use a shading layer to screen itself, i.e. Although we can use SQL expressions to blend channels "live", visual trial and error is a bit tricky. But it is a manual process, and fairly static. We can do any or all of this in Manifold 9, because it is just channel math. I would use either Luminosity, Lighten+Darken, or Overlay blending mode in Photoshop-or more likely a combination, maybe using multiple shading layers from different angles and so on. I don't use Blender but that is just (lack of) habit. (This is the reverse of your layer order, but neither order is definitively right or wrong.) What we really want is to lay down the colour layer(s)-here the 1964 topo image-then overlay the shading layer and only use it for shading-not to blend it as if it were also a colour layer. This means that any blending necessarily reduces contrast. I have never wondered deeply enough what it is, but I imagine it is just a simple weighted averaging of pixel values converted to display RGB, something like underlying layer(s) + overlying layer x opacity. This might be an annoying answer, or not an answer at all, but the difficulty here is that we don't have blending modes between layers in Manifold. Can that be done in another channel and styled to give the hillshade effect?Ħ4 GEOTiff, transp and contrast w-DEM.jpg And I'm thinking the solution lies in the Alpha and Join manipulations, but I'm missing some logic to join the 3-dimensionality from the DEM into the GEOTiff. I'm hoping Manifold can cut out the Blender step to create a full range of contrast in the resulting tiff image. Others making these types of maps are using Blender to drape the tiff over a terrain created from a GIS program. Note the loss in detail in the GEOTiff when making it translucent. Next is the same detail at 50% transparencyĪnd finally the same detail with DEM turned on underneath. Here's a detail of GEOTiff topo Image from US Dept of the Interior dated 1964 Here's where I am so far on that project. That process is not intuitively obvious at all.Īt 7:57 into the video, the narrator suggests the approach could be used to view imagery over terrain elevation data. The Mask field, added off camera, tripped me up. After a false start or two I was able to Knock Out Pixels using Join and Alpha.
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