Painting terrain

Draw mode is where you block a section in. Everything here is live, quick and can be undone. What you paint is a guide the terrain model reads, so the useful question at every stroke is whether the model will keep what you drew or replace it. This page covers the whole paint surface and answers that question first.

What painting is for#

You author a rough shape. Generate keeps your coarse structure and your coastline and invents everything finer. Colour and water coverage follow from the finished heightfield. The River and Lake tools author the valleys and basins that guide that water.

Three facts set the floor on detail.

The paint surface is capped at 1,024 px on its long edge. When you enter Draw mode, the section is shown at that size. On a 4,000 km section one paint pixel is about 3.9 km of ground; on a 200 km focus area it is about 200 m.

Apply changes only adds your change. Untouched ground keeps its full-resolution detail exactly. Ground you painted keeps its detail too, with your change laid over the top.

Generate reads the section on a coarse grid. The cell is a fixed ground size per model: 23 km for the 90 m model, 7.7 km for the 30 m model, about 23.6 km for Base-lite. Anything finer than one coarse cell is averaged away before the model sees it.

What is worth painting#

• Where land is and where sea is.
• The footprint and rough height of a massif, a plateau, a basin, a rift.
• Continental shelf and deep sea floor. The model reads the sea floor as well as the land, so a flat ocean reads to it as a featureless floor and it will give you one back.
• Absolute plateau heights in metres, if you are building a contour-style section for Deterrace.
• Köppen climate, on the Biome layer. That layer is never touched by Generate.

What Enhance replaces#

• Individual ridge lines, spurs, cirques and valley detail. The model authors these.
• Fine river channels. Author rivers and lake basins after Generate or Enhance when you want to retain their shape; another generation can replace detail below its coarse grid.
• Erosion texture and small-scale roughness.
• Anything narrower than one coarse cell of the model you intend to run.

Two exceptions are worth knowing. The coastline tools write at full resolution, bypassing the 1,024 px surface, so a traced coast survives at full detail. And in the Generate dialog, turning Model authors coastline off preserves your land and sea boundary exactly.

Rivers and lake basins#

On the Height layer, choose River and click points from the source downstream, or start from Detect rivers (below). Remove last point takes back the latest click. The preview cuts a descending channel to an outlet, digging through any rise in its way and extending the last point to the nearest outlet. End a new river on a river you already drew and it snaps into that river and feeds it, so its flow joins the larger one downstream. Drawn rivers join the section's own drainage, so the green banks, the widening downstream and the exported water mask follow them like any other river. Crossing a river over itself is refused.

Meander (0 to 1) controls broad alternating bends. Higher values make gentle reaches more sinuous, with smaller bends that favour low ground inside the broader valley. Bends stay close to the route, keep your clicked points, and ease off on steep reaches. At 0 the river runs straight between points, and closely spaced points leave less room to bend. The river is a fixed sinuous channel: banks do not migrate and oxbows do not form over time.

Detect rivers proposes up to twelve main drainage routes from the current heightmap, largest first. A route's source sits where enough water has gathered to flow (about 0.1 m³/s), so wet catchments start farther upstream and dry catchments start lower down or propose nothing. Pick a route from the Detected route list to preview it with its length, estimated discharge at the outlet and the height of the highest obstruction it has to cut through. Detection follows low ground and tells the open sea apart from enclosed hollows. These are proposals: a route through freshly generated terrain may need deep cuts, which the preview and Maximum terrain cut show before you apply. Very short reaches (under about 8 km) are left out.

Detection uses the selected climate month, including snowmelt, or annual runoff in Annual mode. A dry region stays dry. Without monthly climate, Dayside estimates runoff from annual rainfall; without that either, it falls back to a uniform estimate and labels it. The runoff source is shown beneath the route picker. Changing the climate month clears the proposals; run Detect rivers again for the new month.

Drag any waypoint dot to move it, on detected and hand-drawn routes alike. The route recalculates when you release, keeping the other waypoints and the current valley, meander, width and cut settings. Selecting another detected route replaces the pending one. Cancel discards it; Apply river writes it as one undoable terrain edit. Once applied, a river cannot be reopened for editing: undo it and draw it again.

Include tributaries traces the side catchments that feed the proposed channel; dots mark their headwaters. Tributaries need a catchment of at least 25 km² and a reach of about 8 km, up to 64 branches. They only make shallow cuts, so a tributary blocked by high ground is shortened or left out rather than carved through a mountain. Catchments stop at the section edge.

Maximum terrain cut sets how deep the main river may dig (1 to 5,000 m, default 2,000 m). A route needing a deeper cut reports an error, so you can follow lower ground or raise the limit. Tributaries get a much smaller limit (5 m by default), so blocking ground can shorten or remove them when you save.

River width scale is an artistic multiplier (0.25× to 100×, default 1×). Width grows with the water each reach carries and steps up at confluences, starting narrow at the source. A river that reaches the sea opens out over its last stretch into a wider mouth; inland ends and tributaries do not. The multiplier changes how wide the river looks without changing how much water it carries. The width at 1× follows the hydraulic geometry approach with a typical coefficient, as a sensible starting point. Rivers narrower than one output pixel still keep a thin visible line, and tributaries stay finer than the main river.

The preview reports Maximum river width in metres, bank to bank at the widest point, including River width scale and the mouth. It updates as you change the route or the multiplier. On a section with no ground scale it reads as unavailable.

Valley width sets the widest span the river may excavate, in ground units (pixels on a section with no ground scale). A faint sand-coloured band shows it around the blue channel. Gentle ground gets a shallow, narrow cut; reaches blocked by higher ground use more of the width, which gives them gentler sides. The cut lowers the banks while keeping the ridges and hollows around them. Tributaries use a narrower valley. Lakes use Size for basin excavation.

Seasons and water colour#

With monthly climate, the selected month's rainfall and snowmelt set how much water each river carries. The saved channel is wide enough for the wettest month; dry months narrow the water inside it, and a month with no runoff exposes a dry sediment bed. Without monthly climate, Dayside estimates the season from annual rainfall. Lake outlines keep the footprint you chose all year.

River and lake water carries sediment washed in from its own catchment, so its colour depends on the ground upstream. Wetter, steeper and softer-rock catchments give muddier water; well-vegetated ones give clearer water. Coarse sediment settles quickly in a lake while fine silt and clay stay suspended longer, so inflows look more coloured than the open lake. The water does not borrow the colour of the rock around it. River width is purely visual and does not change the sediment. Rivers that reach the coast also feed sediment into the sea near their mouths, and with Water simulation enabled their sediment drifts with the currents. The River sediment water dial scales how strongly sediment shows. The estimates follow published approaches: USDA WEPP for soil loss, the Rubey particle fall-velocity relation for settling, and the reservoir settling approach for lakes. They are appearance estimates for a typical month, and storms, floods and lake currents are not simulated.

Lakes#

Choose Lake and brush a stroke over the basin area. The stroke marks where to look; it does not stamp its shape into the water. Dayside widens the low ground a little, then fills the hollow to the level where it would spill over. The shoreline follows slopes and ridges and can enclose dry islands. Depth controls how strongly the basin is shaped. On a slope the lake may fill only the lower part of the stroke. Keep the footprint inside the section so the shoreline can close. Release to preview, then Apply lake. Each new stroke replaces the pending preview, so apply one basin before drawing another.

Suggest lakes in the Lake tool checks the 64 largest basins on the current terrain against the climate's water budget and lists the top ten, ranked by how full the budget keeps them, each with its area, its fill percentage and whether it is closed or overflowing. Author rivers first: the suggestions read the current drainage. Pick one from the Lake list, then adjust it:

• Evaporation scale, 0.25 to 4, raises or lowers how much water the lake loses to evaporation.
• Lake level (m) overrides the level the budget settled on, up to the basin's spill level. Use equilibrium level returns to the budget's own level. On a world with monthly climate the field reads Initial lake level (m) and the button Use repeating seasonal cycle.

The panel prints the basin's area, depth and spill level, and its balance of inflow, rainfall, evaporation and outflow. Then click Apply lake. One lake is applied per Apply, so suggest again for the next. An overflowing basin keeps its outflow in the budget, and its outlet river is yours to draw. Lakes, suggested or brushed, are the only standing water inland.

Applying and exporting water#

Apply river or Apply lake adds one step to the paint history; Cancel or Escape discards the preview, and changing tools does the same. Undo and redo restore both the terrain and the water, and Apply changes saves both with the section. When you save, the channel and basin are also cut into the full-resolution heightmap. Authored rivers and lakes always show in colour, water masks and water heights, even with the automatic river and lake layers turned off.

The exported Water mask includes authored rivers and lakes. White means water, black means dry land, and grey marks partly wet bank pixels. Use it to mix reflective water and land materials, or to give water a low roughness. The mask follows the selected month, so exposed dry-season banks are not marked as water.

Entering Draw mode#

Click Draw in the top bar, or the brush icon on the left rail (Height brush (Draw mode)), which also selects the Height layer and the Draw tool in one action. The layers icon below it (Biome layer) does the same for the Biome layer.

The left rail carries three view tools that stay available while you paint: Inspect, Pan (drag canvas) and Fit. All rail buttons are disabled while changes are being applied.

Canvas zoom runs from 0.6 to 3.0, with a zoom cluster bottom-right. Hold Space at any time for a temporary pan, the same override Photoshop, Krita and Figma use. The cursor becomes a grab hand and the brush ring is hidden. The pan ends on key up, and also whenever the window loses focus or is hidden, so it cannot get stuck held down.

The Paint layer switch at the top of the Controls panel toggles Height and Biome. Brush size is shared between the two. Nothing else is.

Sea level#

The Sea level slider sits at the top of the Height brush group and moves the waterline the whole section is measured against.

At 0 or 1 the panel warns that the map can end up all land or all sea with no usable coastline. Once a section has been through Generate you also get: Changing sea level after Generate reclassifies model-authored land and ocean. Prefer setting it before Generate. Take that seriously. Moving the waterline changes which model-authored ground counts as land.

Applying a sea-level change re-measures every height against the new waterline and resets the slider to 0.50.

Brush modes#

Six tiles sit under the Brush mode group label on the Height layer.

Switching away from Coast, Landmass, River or Lake cancels any pending preview.

Shared brush controls#

These sliders appear under the Shared band, and only in Set height mode. Stamp, Landmass and Coast have their own controls instead. Size is also on the Biome layer.

The size range is fitted to the section, so the slider's travel stays useful on a 100 km focus area and on a whole continent. Until you move it yourself the brush defaults to 3 % of each new section's short edge. Once you set a size it sticks, and moving to a section at a different resolution keeps the same ground size.

On a section that records no ground scale the brush is sized in pixels instead and the panel says so: THIS SECTION RECORDS NO GROUND SCALE, SO THE BRUSH IS SIZED IN TEXELS.

Falloff and Edge hardness are different on purpose. Falloff shapes a soft additive dab. Edge hardness sets how much of the brush is a flat top, and it defaults hard because a soft skirt around a plateau writes a spread of in-between heights, which is exactly what Deterrace cannot read as a level.

The height brush#

Set height mode has four sub-modes under the Set height band, selected in the Height brush mode group.

Relative mode#

A Lower (carve) toggle flips the brush from raise to carve.

Strength builds up both as you move and as you hold still: keep the brush in place to keep building a hill. Coming back to a window that was minimised mid-stroke does not dump a sudden pile of elevation under the cursor.

The absolute modes#

Set, Raise to and Lower to all write toward a Target height.

The target range always reaches at least -6,000 m to +9,000 m, so abyssal ocean stays within reach even on a blank, flat world. Targets beyond the section's current range are fine: Apply changes widens the range to fit. The cost is that heights across the whole section are stored in slightly coarser steps. The panel says so when it applies, naming the section's current range.

Sampling a height#

Alt-click the canvas to sample the height under the cursor straight into Target height. With Snap to levels on, the sample lands on the nearest saved level. The eyedropper button beside the number field does the same for whatever the cursor is currently hovering; its tooltip reads Use 1,240 m from under the cursor when a sample is available.

The level palette#

Under the Level palette band, + Add current (1,200 m) saves the current target as a level. Levels are kept in ascending order, rounded to the nearest metre, without duplicates. Each is a chip you can click to reuse or remove with its X. [ and ] step the target down and up through the palette.

The palette is what Deterrace reads. Paint your plateaus at palette levels, then run Deterrace to melt the risers into ramps.

Stamps#

Stamp mode places measured real-world landforms. The pack holds 55 tiles, spanning 13.5 km to 6,500 km of ground across ten classes.

Range and Region are the large stamps, sized for whole-continent sections. At a 200 km focus area they will overrun, and the panel says so, quoting the placed span and telling you to scale it down or pick a smaller landform.

The category picker#

Classes are collapsible boxes with one open at a time. Each header shows a thumbnail, the class label and its tile count. Each tile shows a thumbnail, its class name and its true ground extent, with a tooltip reading Rift · 156 km across · 1,850 m relief. The thumbnails are all the same size whatever the landform's real extent, so the size is stated everywhere the tile appears.

With nothing selected, the panel tells you to pick a landform and click once on the canvas: one click, one mountain. The stamp does not build up as you drag.

Placement controls#

Jitter and the ghost#

Jitter turns one selection into a scattered distribution. Its label reads vary each stamp. Two sub-toggles follow.

With jitter on, Scale and Rotation become range sliders, and each placement picks a value inside the range. Scale defaults to 0.65× to 1.5×, spread so small and large sizes come up equally often. Rotation defaults to the full -180° to 180°.

The ghost cursor shows the outline of the exact placement that will land, including the jittered tile, size, heading and mirror. It changes only when a placement lands, the jitter settings change or the selection changes; moving the mouse never re-rolls it, so what you see is what the click places. The outline traces where the stamp actually changes the ground, so it never promises relief in the tile's corners that the brush will not lay down.

Landmass shapes#

Landmass mode places real Natural Earth island outlines as land or sea decisions. The library holds 5,090 outlines in five size bands.

The grid shows a sample of 24 outlines per class, spread evenly from the smallest to the largest, and says so under it: showing 24 of 1,743 real outlines. Jitter still draws from the whole class, and the footer says that too.

Placing#

The Landmass operation switch chooses Add land or Remove land. Remove erases with the same outlines, which is how a bay, a strait or a lagoon gets a real coastline instead of a circle.

Each click stages one placement. Place as many as you like; together they make one coastline. The batch previews live on the map, and the status line reads 4 placed · 18,204 px would change · tune or apply.

Jitter scale defaults to 0.75× to 1.35×, tighter than the stamp pack's spread, because Vary example already draws a different real island each click and a wide size range on top of that reads as noise.

Scaling past the real island#

The library stops at islands of 1,500 km², so every outline is an island. Authoring a continent means scaling one up. Above 5× the panel says exactly what you have done: at that multiplier this is no longer a 21 km island, it is that island's outline used as a continental silhouette. Coastlines look alike at every scale, so a 21 km island's shape still reads as a believable coast at 157 km. The size is your choice, and the panel makes that explicit.

Coastline detail and sea floor#

Landmass shares one set of coastline and sea-floor settings per section with the Coast lasso.

The size of bays and islands is fitted to the section automatically, so they stay in proportion on a small island and on a continent.

Applying#

Apply coastline writes a new heightmap at full resolution with a real sea floor. Undo last drops the most recent placement. Cancel discards the batch. A landmass previews from the applied terrain, so unapplied strokes block it. The panel says your painted changes are not applied yet, that a landmass previews from the applied terrain and would discard them, and tells you to use Apply changes first.

The coast lasso#

Coast selects a region. It is neither a brush nor a fill. Paint land with the height brushes, run Apply changes, then trace a loop around a stretch of coast. On release the coastline inside the loop is redrawn from the terrain you painted: rugged over relief, calm over flats, with a real continental margin. Nothing outside the loop changes.

Tracing does not commit. It stages the selection and the canvas shows a live preview at the paint resolution. Every setting below updates the preview, so you tune the coast on the map. The canvas badge reads Updating coastline… while it works, then invites you to adjust or apply, or reports that the preview failed and asks you to adjust the settings. The panel reads Preview on the map · 24,110 px would change · tune or apply.

Apply coastline then writes it at full resolution and Cancel discards it. The same unapplied-paint guard applies: the lasso previews from applied terrain, so paint has to be applied first.

Coastline shape#

Sea floor#

The biome brush#

Switch Paint layer to Biome and you paint Köppen classes directly. This layer is never touched by Generate, and the climate you paint takes priority over Dayside's own latitude-based estimate wherever colour is worked out.

The Köppen picker#

Classes are grouped by macro biome: Tropical, Arid, Mediterranean, Temperate, Boreal, Tundra, Ice. Each group is a grid of chips carrying the class colour swatch and its code. Classes already present in the map sort first and carry the tooltip Cfb · present.

The full list, in order: Af, Am, Aw, BWh, BWk, BSh, BSk, Csa, Csb, Csc, Cwa, Cwb, Cwc, Cfa, Cfb, Cfc, Dsa, Dsb, Dsc, Dsd, Dwa, Dwb, Dwc, Dwd, Dfa, Dfb, Dfc, Dfd, ET, EF. The default selection is Cfb.

A world with no biome layer shows THIS WORLD HAS NO BIOME LAYER. and a Create biome layer button, which confirms with FILL THE MAP WITH Cfb (TEMPERATE)? THIS IS UNDOABLE. Creating the layer is a history entry like any other, so undo reaches it.

Guide overlay#

The Guide overlay group sits apart from the layer controls, because a guide is traced with both brushes. It is collapsed by default. The same control is in the globe workspace side panel, and one guide selection is shared between the globe and the paint surface.

Choose guide image… opens your system's file picker. Accepted formats are PNG, JPEG and WebP, up to 64 MB, 16,384 px on either side, and no more than 8,192 × 8,192 pixels in total. A world holds 12 guides. The list carries a No guide entry plus one row per image with a thumbnail, name and pixel size, each removable.

The editor shows the guide as it falls on this section, so a whole-world (equirectangular) guide is projected onto the section rather than squashed into the crop. On a whole-world project a guide that is not 2:1 gets a warning, because the globe wraps a guide as a full world map and any other shape stretches.

Applying changes#

Apply changes saves the whole paint session to the section's heightmap. It is disabled when there is nothing to undo, while changes are being applied, and while an enhance job runs.

What happens when you apply:

• Only ground you actually changed is written, on the height and biome layers alike.
• Your height change is laid over the full-resolution heightmap, so untouched ground keeps its detail.
• Biome classes keep hard boundaries at full resolution.
• If you moved the sea level, every height is re-measured against the new waterline and the slider returns to 0.50.
• The section's refined coastline is marked out of date.
• The undo history is reset. The applied result becomes the new starting point, and the strokes behind it are gone.

That last point is the one to remember. Undo covers a paint session. It does not walk back across an Apply.

Revert is a different mechanism. It restores the hand-authored heightmap from a copy saved the first time you ran Generate on that section, and it appears in the Generate and Deterrace dialogs. A section that has never been generated has no saved copy and no Revert. The Coast and Landmass panels mention that revert is available afterwards; that promise holds only for a section that has been generated at least once.

Paint history and undo#

The history icon on the left rail (Paint history in Draw mode) toggles the Paint history group. It carries Undo and Redo buttons and a list of strokes, newest first, with the current position tagged CURRENT and a final row Original terrain.

Stroke labels state what the stroke did: Raise stroke, Lower stroke, Set 1,200 m, Raise to 800 m, Lower to 0 m, Cfb biome stroke, Stamp <tile>, Sea level 0.62, Create biome layer.

History holds 20 strokes plus the original terrain. Past that, the oldest stroke is dropped, so the deepest undo jumps from the oldest remaining stroke straight back to the original terrain.

Landmass placements are the exception: they add nothing to the paint history, because nothing has been written to the heightfield yet. Use Undo last in the Landmass panel instead.

Erode#

Erode in the section top bar carves drainage into the section's heightfield by simulating a long stretch of landscape history: rivers cut valleys, slopes between them soften, and water spreads across every downhill path by default. It is the tool for a section whose relief is there but whose valleys do not join up. It runs in the background, and the top-bar button reads Eroding N% while it runs. You can close the panel and the run continues.

The panel asks its questions in this order.

Further down, Multi-resolution carves the main valleys on a coarse grid first, the noise controls set the small bumps that start channels, and Physics shows the preset's erodibility, hillslope diffusivity, uplift, step length and step count. Greyed values come from the preset; type over one to override just that one.

Cancel stops the run and leaves the heightmap untouched. Revert restores the heightmap from before the last Erode.

Deterrace#

Deterrace melts the risers of a stepped, contour-style heightmap into ramps while every pixel stays inside the elevation band it was drawn in. It is the companion to painting plateaus at palette levels. It works on land only and leaves the sea floor exactly as it is. Open it from the top bar.

The dialog detects levels for you and scores the section, reporting how many levels it found and what share of land sits on one. When fewer than 75 % of land pixels sit on a level it says instead: Only 31% of land sits on a detected level, so this section does not look like a contour map. Running it is harmless, but there may be little to melt. It discourages; it never blocks.

The level table is editable and takes one number per level: the elevation the band was drawn at, in metres. A level's pixels may move anywhere between it and the next level up, which the Up to column shows beside each row. The top level runs up to Max height, a single field under the table that starts one contour step above the top level (or at the highest land found, whichever is higher). Set it equal to the top level to keep the summit flat. Share is the fraction of land sitting on each level. Rows have a remove button and Add level appends one step above the top, lifting the max height clear of it if it has to.

A warning states the real consequence: changing the heightmap makes this section's refined coastline out of date, so you will need to refine it again afterwards. The dialog cannot be dismissed by clicking outside it or the close X while a run is in progress.

Keyboard shortcuts#

Shortcuts do nothing while you are typing in a field. All of them except releasing Space require Draw mode.

In Stamp or Landmass mode with something selected, the bracket keys resize the placement; otherwise they step the target height. They only act on the Height layer, so a stamp left selected never takes over the keys on the Biome layer.

The heads-up display#

In Draw mode with the Draw tool, two readouts sit on the canvas.

Height under cursor shows a signed metre value against a range bar labelled with the section's minimum, section range · m, and its maximum. Height layer only.

The brush line changes with the mode. A brush reads ⌀ 40 km plus a suffix: · RAISE, · LOWER, · SET 1,200 m, · RAISE TO 800 m or · LOWER TO 0 m. A placement reads its ground span and heading, 157 km · 34°, with ↔ or ↕ for mirrors, · jitter when jitter is on, and · LAND or · REMOVE for landmass. On a section with no ground scale the brush reads in pixels.

There is no equivalent readout in Render mode.

Editing large sections#

Open a section big enough to need it and Dayside offers a working-resolution proxy. The prompt quotes the section's pixel size and megapixel count, and warns that editing terrain at full resolution is slow enough that a single coastline edit can take minutes. Pick a resolution below native and your full-resolution master is kept untouched. The choice is remembered per section, so it never asks again.

While a proxy is active a banner sits under the top bar: Editing at 4K · native 16,384×16,384 · 3 edits not yet baked. Bake to native replays your edits onto the full-resolution master. Discard throws the proxy edits away and restores the untouched master.

The bake is never automatic. It is an explicit button.