Getting pretty good results on full res gpu renders since removing block to scale by sample rate

compare-skipmip.ps1

@@ -5,7 +5,8 @@
 #   .\compare-skipmip.ps1 -Scene "path\to\scene.pbrt" -Spp 16
 #   .\compare-skipmip.ps1 "scene.pbrt" 16
 #   .\compare-skipmip.ps1 "scene.pbrt" 16 -ShowProgress --gpu
-# Omit -Spp to use Integrator "integer pixelsamples" from the .pbrt file (same as pbrt.exe without --spp).
+#   .\compare-skipmip.ps1 "scene.pbrt" -ShowProgress --gpu   (--gpu is not parsed as Spp; use -Gpu or trailing --gpu)
+# Omit -Spp and any leading digits-only tail so pbrt.exe does not get --spp (scene Integrator "integer pixelsamples" applies).
 #
 # Render progress: stdout is written to the .txt log live while pbrt runs (poll ~8 Hz for console echo).
 # Optional -ExtraPbrtArgs is appended for both runs (e.g. --wavefront).
@@ -19,8 +20,10 @@ param(
     [Parameter(Mandatory = $true, Position = 0)]
     [string] $Scene,
 
-    [Parameter(Mandatory = $false, Position = 1)]
-    [int] $Spp = 0,
+    # Named only (no Position): so trailing tokens like --gpu go to RemainingArguments, not here.
+    # Optional positional spp: first RemainingArguments token that is all-digits (>= 1) when -Spp omitted.
+    [Parameter(Mandatory = $false)]
+    $Spp = $null,
 
     [string] $PbrtExe = "",
     [string] $LogDir = "",
@@ -295,32 +298,59 @@ $logNoMip = Join-Path $LogDir ("{0}-{1}-nomip.txt" -f $base, $stamp)
 $logSkipMip = Join-Path $LogDir ("{0}-{1}-skipmip.txt" -f $base, $stamp)
 $summaryPath = Join-Path $LogDir ("{0}-{1}-comparison.txt" -f $base, $stamp)
 
+$sppForCli = $null
+$sppFromNamed = $false
 if ($PSBoundParameters.ContainsKey('Spp')) {
-    if ($Spp -lt 1) {
+    $sppFromNamed = $true
+    if ($null -eq $Spp -or "$Spp" -eq '') {
+        throw "Spp was specified but is empty; omit -Spp to use the scene file default."
+    }
+    try {
+        $sppForCli = [int]$Spp
+    } catch {
+        throw "Invalid Spp value (expected positive integer): $Spp"
+    }
+    if ($sppForCli -lt 1) {
         throw "Spp must be >= 1 when specified (omit -Spp to use the scene file default)."
     }
 }
 
+$tailPbrt = New-Object System.Collections.Generic.List[string]
+if ($RemainingArguments) {
+    foreach ($a in $RemainingArguments) {
+        $tailPbrt.Add($a)
+    }
+}
+if (-not $sppFromNamed -and $tailPbrt.Count -gt 0) {
+    $head = $tailPbrt[0]
+    if ($head -match '^\d+$') {
+        $trySpp = [int]$head
+        if ($trySpp -ge 1) {
+            $sppForCli = $trySpp
+            $tailPbrt.RemoveAt(0)
+        }
+    }
+}
+
 $common = @(
     $sceneFull,
     "--stats"
 )
-if ($PSBoundParameters.ContainsKey('Spp')) {
-    $common += @("--spp", "$Spp")
+if ($null -ne $sppForCli) {
+    $common += @("--spp", "$sppForCli")
 }
 $common += $ExtraPbrtArgs
 
 $gpuWanted = [bool]$Gpu
-$tailPbrt = New-Object System.Collections.Generic.List[string]
-if ($RemainingArguments) {
-    foreach ($a in $RemainingArguments) {
-        if ($a -eq '--gpu') {
-            $gpuWanted = $true
-        } else {
-            $tailPbrt.Add($a)
-        }
+$finalTail = New-Object System.Collections.Generic.List[string]
+foreach ($a in $tailPbrt) {
+    if ($a -eq '--gpu') {
+        $gpuWanted = $true
+    } else {
+        $finalTail.Add($a)
     }
 }
+$tailPbrt = $finalTail
 if ($gpuWanted -and ($common -notcontains '--gpu')) {
     $common += '--gpu'
 }
@@ -328,7 +358,7 @@ if ($tailPbrt.Count -gt 0) {
     $common += [string[]]$tailPbrt.ToArray()
 }
 
-$sppLabel = if ($PSBoundParameters.ContainsKey('Spp')) { "$Spp" } else { "(scene file default)" }
+$sppLabel = if ($null -ne $sppForCli) { "$sppForCli" } else { "(scene file default)" }
 
 Write-Host "=== pbrt compare-skipmip ===" -ForegroundColor Cyan
 Write-Host "pbrt:    $PbrtExe"

src/pbrt/cpu/render.cpp

@@ -33,7 +33,7 @@ void RenderCPU(BasicScene &parsedScene) {
     Sampler sampler = parsedScene.GetSampler();
 
     LOG_VERBOSE("Image texture mip preprocess");
-    RunImageTextureMipPreprocess(parsedScene, camera, sampler.SamplesPerPixel());
+    RunImageTextureMipPreprocess(parsedScene, camera);
 
     // Textures
     LOG_VERBOSE("Starting textures");

src/pbrt/texture_mip_preprocess.cpp

@@ -399,8 +399,7 @@ static bool AffineTripleScalarGradients2D(Float x0, Float y0, Float x1, Float y1
     return true;
 }
 
-static Float MinPrimaryContinuousLodForUse(const Camera &camera, int samplesPerPixel,
-                                           const ImageTextureGeometryUse &use,
+static Float MinPrimaryContinuousLodForUse(const Camera &camera, const ImageTextureGeometryUse &use,
                                            int pyramidLevels, Allocator alloc) {
     (void)alloc;
     if (!Options || Options->disableTextureFiltering || !use.localTriangles ||
@@ -422,10 +421,6 @@ static Float MinPrimaryContinuousLodForUse(const Camera &camera, int samplesPerP
     const Transform &worldFromShape = use.worldFromShape;
     Bounds2i pb = proj->GetFilm().PixelBounds();
 
-    Float sppScale = 1.f;
-    if (!Options->disablePixelJitter)
-        sppScale = std::max<Float>(0.125f, 1.f / std::sqrt(Float(samplesPerPixel)));
-
     constexpr Float kMinW = 1e-6f;
 
     auto lodForTriangle = [&](const ImageTextureMeshTriangle &tri) -> Float {
@@ -484,11 +479,6 @@ static Float MinPrimaryContinuousLodForUse(const Camera &camera, int samplesPerP
         Float dudy = (dUow_dy - u * dIw_dy) / inv_w;
         Float dvdy = (dVow_dy - v * dIw_dy) / inv_w;
 
-        dudx *= sppScale;
-        dvdx *= sppScale;
-        dudy *= sppScale;
-        dvdy *= sppScale;
-
         if (!IsFinite(dudx) || !IsFinite(dvdx) || !IsFinite(dudy) || !IsFinite(dvdy))
             return Infinity;
 
@@ -532,9 +522,8 @@ static Float MinPrimaryContinuousLodForUse(const Camera &camera, int samplesPerP
 }
 
 int ComputeImageTextureSafeDownsizesFromPreprocess(
-    const Camera &camera, int samplesPerPixel,
-    const std::vector<ImageTextureGeometryUse> &usesForTexture, int mipmapPyramidLevels,
-    Allocator alloc) {
+    const Camera &camera, const std::vector<ImageTextureGeometryUse> &usesForTexture,
+    int mipmapPyramidLevels, Allocator alloc) {
     if (usesForTexture.empty())
         return 0;
 
@@ -562,8 +551,8 @@ int ComputeImageTextureSafeDownsizesFromPreprocess(
         size_t i = (size_t)ui;
         if (bailForZeroPairSafe.load(std::memory_order_relaxed))
             return;
-        Float minLod = MinPrimaryContinuousLodForUse(
-            camera, samplesPerPixel, usesForTexture[i], mipmapPyramidLevels, alloc);
+        Float minLod =
+            MinPrimaryContinuousLodForUse(camera, usesForTexture[i], mipmapPyramidLevels, alloc);
         minLods[i] = minLod;
         lodComputed[i] = 1;
         if (pairSafeFromMinLod(minLod) == 0)
@@ -610,8 +599,7 @@ int ComputeImageTextureSafeDownsizesFromPreprocess(
     return std::max(0, textureMinSafeDownsizes);
 }
 
-void RunImageTextureMipPreprocess(BasicScene &scene, const Camera &camera,
-                                   int samplesPerPixel) {
+void RunImageTextureMipPreprocess(BasicScene &scene, const Camera &camera) {
     ClearImageTextureMipDownsizeOverrides();
     if (!Options || !Options->skipMipImageTextures)
         return;
@@ -654,8 +642,8 @@ void RunImageTextureMipPreprocess(BasicScene &scene, const Camera &camera,
                     "  (no trianglemesh/plymesh reflectance imagemap uses found; safe downsizes 0)\n");
             }
         } else {
-            safeDownsizes = ComputeImageTextureSafeDownsizesFromPreprocess(
-                camera, samplesPerPixel, uses, pyramidLevels, alloc);
+            safeDownsizes =
+                ComputeImageTextureSafeDownsizesFromPreprocess(camera, uses, pyramidLevels, alloc);
         }
 
         if (MipPreprocessLogDetail())

src/pbrt/texture_mip_preprocess.h

@@ -45,15 +45,14 @@ struct ImageTextureGeometryUse {
 // perspective/orthographic; spherical/realistic cameras yield 0 safe downsizes). UV imagemap
 // on reflectance for diffuse / coateddiffuse / diffusetransmission and mix thereof;
 // trianglemesh + plymesh; includes ObjectInstance placements (transformed into render space).
+// Independent of integrator samples per pixel (screen-to-texture footprint uses the pixel grid).
 int ComputeImageTextureSafeDownsizesFromPreprocess(
-    const Camera &camera, int samplesPerPixel,
-    const std::vector<ImageTextureGeometryUse> &usesForTexture, int mipmapPyramidLevels,
-    Allocator alloc);
+    const Camera &camera, const std::vector<ImageTextureGeometryUse> &usesForTexture,
+    int mipmapPyramidLevels, Allocator alloc);
 
 // Clears prior overrides, then assigns per-file safe downsizes before image loads.
 // No-op when --skipmip is off (aside from clearing stale overrides).
-void RunImageTextureMipPreprocess(BasicScene &scene, const Camera &camera,
-                                   int samplesPerPixel);
+void RunImageTextureMipPreprocess(BasicScene &scene, const Camera &camera);
 
 }  // namespace pbrt
 

src/pbrt/wavefront/integrator.cpp

@@ -115,7 +115,7 @@ WavefrontPathIntegrator::WavefrontPathIntegrator(
     sampler = scene.GetSampler();
 
     LOG_VERBOSE("Image texture mip preprocess");
-    RunImageTextureMipPreprocess(scene, camera, sampler.SamplesPerPixel());
+    RunImageTextureMipPreprocess(scene, camera);
 
     // Textures
     LOG_VERBOSE("Starting to create textures");