[WIP] "Lochinvar" Clyde puffer

[kapuhy]

Originally Posted by Mister_M

Other than that, one quick question : what is the sail used for, as there is already a propeller ? I doubt that it's used for propulsion purpose. Maybe for lateral maneuvers ?

That, and I guess with some older puffers you want to have backup propulsion in case your ancient steam engine fails.

[Mister_M]

Originally Posted by kapuhy

That, and I guess with some older puffers you want to have backup propulsion in case your ancient steam engine fails.

I doubt that this little sail was enough to move such a boat made in iron or steel, with a heavy engine inside.

But also, I see that this sail has a fixed position and it can't be oriented (only a little by fixing the "flying" cable) to one side or the other, so not very useful to navigate...

Edit : I couldn't find any picture of a Clyde puffer with a sail. It was then probably used only in extreme emergency situations...

[gap]

Originally Posted by Mister_M

1) Ah ok. So there are two "shadowing" parameters involved : ambiant scene light + AO map.

Yes, more or less.

1 - The AO map contains pre-rendered shadows; think of it as the soft shadows cast by diffuse light.

2 - Surface normals are another important factor which determines the luminosity of a surface; the more parallel a normal is to the direction of incident light, the lighter will be the relative surface.

3 - Normals are also affected by object smoothing; this is the hardness of the edges connecting the triangles that compose a curved surface. By default, edges are considered "soft". That means that the normal of each triangle is averaged with the normals of neighbouring triangles, giving the surface a smooth look with subtle changes of luminosity. Nonetheless, edges can be set to "hard", which means that there will be an abrupt change of luminosity between a triangle and the next ones, and that the edges between adjoining triangles will be well noticeable if their normals point to radically different directions.

4 - Finally we have dynamic shadows: the sharp shadows cast on top of an object when another object is blocking light rays for it.

Off the four factors I summarized above, the effect of the last three is subject to quantity and direction of a directional light source (such as the sun), whereas the the first one is static and it is supposed to simulate ambient (i.e. diffuse) light. In my last previews, you can see the effect of the first three of them but, as I wrote yesterday, the illumination I set in Wings3D was actually a diffuse light coming from one side (like the sun light at dusk). In game, a variety of different illuminations will apply depending on time season, time of the day and weather.

Originally Posted by Mister_M

2) Can't you have any preview directly in Autodesk Softimage Mod Tool 7.5 ?

Sure you can, but I don't think the result would much better than in Wings3D. There are specialized 3D rendering programs which simulate materials and realistic light effects, but I never messed with them. A good render might takes hours of of study and of PC calculations. A bit too long for the purposes of a simple previes. I prefer using that time for something else and waiting to see the final result of my work in game

Originally Posted by Mister_M

3) Yes sure. But I was not talking about these objects, but mainly about the large vertical surfaces of the cabin which are all grey instead of white like the hull. And about the lifeboat which is far too much dark in my opinion. So if the texture applied to those meshes is white for example, they will appear grey even if directly exposed to the sun light...

That's the effect of the AO map. Obviously you are expecting all vertical surfaces to be equally illuminated because you have in mind a light source placed about on top of the boat. Nonetheless you should remember that the AO map simulates the occlusion of ambient light: i.e. light coming from all the directions. Vertical surfaces on deck look darker than the hull because light rays coming from the bottom are partially blocked by the hull itself before they can illuminate those surfaces. Once in game, this effect will be balanced by the top sunlight, and boat's shading will look perfectly natural

Originally Posted by Mister_M

4) So the life buoy should not be breakable as there is a dedicated shadow for it on the cabin.

The shadow was much darker because the lifebuoy is very close to the whelhouse's side. I reduced this effect exactly for the reason that you are mentioning. In game, the AO map is blended to the diffuse texture and the undue shadow will be lesser obvious. It will look like the halo left by a frame on a wall, when you remove it, or so I hope. In any case I have that shadow on a separate layer in a psd file. If the final effect won't be satisfactory, I am always in time to make that shdow even more subtle, or to completely remove it.

Originally Posted by Mister_M

5) Other than that, one quick question : what is the sail used for, as there is already a propeller ? I doubt that it's used for propulsion purpose. Maybe for lateral maneuvers ?

Talking in general, a mixed wind/engine propulsion can be used to spare fuel and increase top speed with favourable winds. As I have read, aboard puffers the jib sail was used on occasions. In game, the sail will be set as an optional equipment, so it will be rarely seen.
The plan that this model is based on also features a mainsail, but that was used very rarely (probably in case of emergencies as noted by kapuhy) and I decided not to include it in my model.

[Mister_M]

Thank you for your very detailed, patient and clear explanations. I'm impressed, and happy to learn so many things !

I still have a few comments :

Originally Posted by gap

Obviously you are expecting all vertical surfaces to be equally illuminated because you have in mind a light source placed about on top of the boat. Nonetheless you should remember that the AO map simulates the occlusion of ambient light: i.e. light coming from all the directions.

Yes, IMO no light should come from the bottom to create the AO map of a ship. I think that this is not realistic, because in reality you don't have any sun light coming from the bottom, but only very little light reflection by the sea. So, the solution (to avoid "undue" shadow on the cabin) would be to create the AO map on the cabin without the ship's deck occluding the light.

Originally Posted by gap

Once in game, this effect will be balanced by the top sunlight, and boat's shading will look perfectly natural

No, because in game the hull will receive as much sun light as the cabin, so the difference of illumination will be noticeable between hull and cabin (more "AO shadows" on cabin).

Originally Posted by gap

Talking in general, a mixed wind/engine propulsion can be used to spare fuel and increase top speed with favourable winds. As I have read, aboard puffers the jib sail was used on occasions. In game, the sail will be set as an optional equipment, so it will be rarely seen. The plan that this model is based on also features a mainsail, but that was used very rarely (probably in case of emergencies as noted by kapuhy) and I decided not to include it in my model.

Ok, I was suspecting something like that. I think it's a good idea to set the sail as an optional element.

[gap]

Originally Posted by Mister_M

But also, I see that this sail has a fixed position and it can't be oriented (only a little by fixing the "flying" cable) to one side or the other, so not very useful to navigate...

Obviously you have never been on a sailboat. With that little degree of freedom, a jib sail can make a modern sailboat to move almost against the wind direction

https://en.wikipedia.org/wiki/Sailing_into_the_wind

Originally Posted by Mister_M

Thank you for your very detailed, patient and clear explanations. I'm impressed, and happy to learn so many things !

My own pleasure

Originally Posted by Mister_M

IMO no light should come from the bottom to create the AO map of a ship. I think that this is not realistic, because in reality you don't have any sun light coming from the bottom, but only very little light reflection by the sea. So, the solution (to avoid "undue" shadow on the cabin) would be to create the AO map on the cabin without the ship's deck occluding the light.

Ambient light is not the same as direct sun light. While I will agree with you that the sea bottom won't reflect as much light as atmoshpere and sea surface, I think that for our purposes this difference can be ignored

Originally Posted by Mister_M

No, because in game the hull will receive as much sun light as the cabin, so the difference of illumination will be noticeable between hull and cabin (more "AO shadows" on cabin).

Even supposing that the different diffuse illumination between hull and vertical superstructure surfaces is irrealistic (but I disagree on that):

a) the difference is so slight that under direct sunlight it will be barely noticeable.

b) the hull will be painted mostly in black and red, whereas the superstructure will have a lighter paint. The one thing you will notice once the model is fully textured and imported in game, is that the bottom part of vertical surfaces, near the deck, is slightly darker than upper parts. This effect is totally realistic and it will enhance the sense of threedimensionality.
You are probably used to SHIII ships, most of which lack an AO map. To me, those models look terribly flat, as if they were photographed from far distance during an hazy day

[Mister_M]

Originally Posted by gap

Obviously you have never been on a sailboat. With that little degree of freedom, a jib sail can make a modern sailboat to move almost against the wind direction

https://en.wikipedia.org/wiki/Sailing_into_the_wind

You're right, I would not be able to "drive" a sailboat. But can this puffer be compared to a thin and light sailboat ? And I was not aware of the extra sail that you mentioned in a previous post.

Originally Posted by gap

Ambient light is not the same as direct sun light. While I will agree with you that the sea bottom won't reflect as much light as atmoshpere and sea surface, I think that for our purposes this difference can be ignored

I was not talking about the sea bottom, but about the direction from which may come direct sun light (which obviously can't come from the sea bottom).